v3.25.1
Unaudited Consolidated Schedule of Investments (Additional Information)
€ in Millions, £ in Millions, kr in Millions, $ in Millions, $ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2025
USD ($)
Mar. 31, 2024
USD ($)
Dec. 31, 2024
USD ($)
Mar. 31, 2025
CAD ($)
Mar. 31, 2025
EUR (€)
Mar. 31, 2025
GBP (£)
Mar. 31, 2025
SEK (kr)
Dec. 31, 2024
CAD ($)
Dec. 31, 2024
EUR (€)
Dec. 31, 2024
GBP (£)
Dec. 31, 2024
SEK (kr)
Derivative [Line Items]                      
Value at Settlement $ 190.0   $ 148.8                
Current Value 197.9   146.8                
Gross Amount of Recognized Assets 0.0   3.0                
Derivatives Available for Offset 0.0   (1.0)                
Total     $ 2.0                
Unrealized Appreciation (Depreciation) $ (7.9)                    
Percent of net assets 215.70% [1]   203.70% [2] 215.70% [1] 215.70% [1] 215.70% [1] 215.70% [1] 203.70% [2] 203.70% [2] 203.70% [2] 203.70% [2]
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3] $ 13,490.4                    
Net Realized Gain (Loss) (18.0) $ (243.0)                  
Net Change in Unrealized Appreciation (Depreciation) (14.0) 186.0                  
Fair Value, ending balance 14,121.5 [4]   $ 13,490.4 [3]                
PIK Income $ 64.0 25.0                  
Qualifying Assets                      
Derivative [Line Items]                      
Percent of net assets 70.80%   73.20% 70.80% 70.80% 70.80% 70.80% 73.20% 73.20% 73.20% 73.20%
LIBOR                      
Derivative [Line Items]                      
Variable rate     4.85%         4.85% 4.85% 4.85% 4.85%
Euro Interbank Offer Rate (EURIBOR)                      
Derivative [Line Items]                      
Variable rate     2.71%         2.71% 2.71% 2.71% 2.71%
CDOR                      
Derivative [Line Items]                      
Variable rate     4.97%         4.97% 4.97% 4.97% 4.97%
Euro Interbank Offered Rate                      
Derivative [Line Items]                      
Variable rate 2.34%     2.34% 2.34% 2.34% 2.34%        
BBSY                      
Derivative [Line Items]                      
Variable rate 4.18%   4.47% 4.18% 4.18% 4.18% 4.18% 4.47% 4.47% 4.47% 4.47%
Australian Bank Bill Swap Rate                      
Derivative [Line Items]                      
Variable rate 4.13%     4.13% 4.13% 4.13% 4.13%        
STIBOR                      
Derivative [Line Items]                      
Variable rate 2.36%   2.54% 2.36% 2.36% 2.36% 2.36% 2.54% 2.54% 2.54% 2.54%
SONIA                      
Derivative [Line Items]                      
Variable rate 4.36%   4.62% 4.36% 4.36% 4.36% 4.36% 4.62% 4.62% 4.62% 4.62%
Secured Overnight Financing Rate (SOFR)                      
Derivative [Line Items]                      
Variable rate 4.29%   4.31% 4.29% 4.29% 4.29% 4.29% 4.31% 4.31% 4.31% 4.31%
Non-controlled/affiliated                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance $ 1,140.0 745.4 $ 745.4                
Gross Additions 110.9 [5]   451.3 [6]                
Gross Reductions (55.9) [7]   (130.4) [8]                
Net Realized Gain (Loss) 8.9 (10.0) (60.7)                
Net Change in Unrealized Appreciation (Depreciation) (20.3) 20.0 134.4                
Fair Value, ending balance 1,183.6   1,140.0                
Investment Income 8.0 [9]   42.2 [10]                
PIK Income 17.6 [9] 10.0 49.6 [10]                
Fee income 3.4 [9] 0.0 1.1 [10]                
Dividend and Other Income 8.9 [9] 4.0 15.5 [10]                
Controlled/affiliated                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 3,776.7 3,335.7 3,335.7                
Gross Additions 363.4 [11]   1,052.5 [12]                
Gross Reductions (271.8) [13]   (463.1) [14]                
Net Realized Gain (Loss) 12.5 (8.0) 23.2                
Net Change in Unrealized Appreciation (Depreciation) (51.5) (6.0) (171.6)                
Fair Value, ending balance 3,829.3   3,776.7                
Investment Income 15.4 [15]   70.8 [16]                
PIK Income 28.0 [15] 8.0 93.5 [16]                
Fee income 0.0 [15] 0.0 9.3 [16]                
Dividend and Other Income 59.8 [15] 57.0 232.5 [16]                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,CAD March, 2026                      
Derivative [Line Items]                      
Value at Settlement 0.4   0.4 $ 0.6       $ 0.6      
Current Value 0.4   0.4                
Gross Amount of Recognized Assets 0.0   0.0                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,EUR, December, 2029                      
Derivative [Line Items]                      
Value at Settlement 6.6   6.6   € 5.7       € 5.7    
Current Value 6.6   6.5                
Gross Amount of Recognized Assets 0.0   0.1                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,EUR, February, 2028                      
Derivative [Line Items]                      
Value at Settlement 5.2       € 4.6            
Current Value 5.1                    
Gross Amount of Recognized Assets 0.1                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,EUR, February, 2028                      
Derivative [Line Items]                      
Value at Settlement     5.2           € 4.6    
Current Value     5.0                
Gross Amount of Recognized Assets     0.2                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, April 2025                      
Derivative [Line Items]                      
Value at Settlement 1.9   1.9     £ 1.5       £ 1.5  
Current Value 1.9   1.9                
Gross Amount of Recognized Assets 0.0   0.0                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, April, 2026                      
Derivative [Line Items]                      
Value at Settlement 4.3         3.5          
Current Value 4.5                    
Derivatives Available for Offset (0.2)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, April, 2026                      
Derivative [Line Items]                      
Value at Settlement     4.4             3.5  
Current Value     4.4                
Gross Amount of Recognized Assets     0.0                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, August , 2026 1                      
Derivative [Line Items]                      
Value at Settlement     6.0             4.8  
Current Value     6.0                
Gross Amount of Recognized Assets     0.0                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, August , 2026 2                      
Derivative [Line Items]                      
Value at Settlement     10.8             8.6  
Current Value     10.8                
Gross Amount of Recognized Assets     0.0                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, August, 2026 1                      
Derivative [Line Items]                      
Value at Settlement 6.0         4.8          
Current Value 6.1                    
Derivatives Available for Offset (0.1)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, August, 2026 2                      
Derivative [Line Items]                      
Value at Settlement 10.8         8.6          
Current Value 11.1                    
Derivatives Available for Offset (0.3)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, December, 2025                      
Derivative [Line Items]                      
Value at Settlement 35.1         27.8          
Current Value 35.8                    
Derivatives Available for Offset (0.7)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, February 2028                      
Derivative [Line Items]                      
Value at Settlement 11.1   11.1     8.6       8.6  
Current Value 11.0   10.7                
Gross Amount of Recognized Assets 0.1   0.4                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, January, 2026                      
Derivative [Line Items]                      
Value at Settlement 7.5   7.5     6.2       6.2  
Current Value 8.0   7.7                
Derivatives Available for Offset (0.5)   (0.2)                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,GBP, March , 2026                      
Derivative [Line Items]                      
Value at Settlement 16.6   16.6     £ 13.5       £ 13.5  
Current Value 17.4   16.9                
Derivatives Available for Offset (0.8)   (0.3)                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, April, 2025 1                      
Derivative [Line Items]                      
Value at Settlement 2.6           kr 25.7        
Current Value 2.6                    
Gross Amount of Recognized Assets 0.0                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, April, 2025 2                      
Derivative [Line Items]                      
Value at Settlement 2.4           25.7        
Current Value 2.6                    
Derivatives Available for Offset (0.2)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, April, 2027                      
Derivative [Line Items]                      
Value at Settlement 16.4           167.0        
Current Value 17.1                    
Derivatives Available for Offset (0.7)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, April, 2027                      
Derivative [Line Items]                      
Value at Settlement     16.4               kr 167.0
Current Value     15.7                
Gross Amount of Recognized Assets     0.7                
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, December, 2029                      
Derivative [Line Items]                      
Value at Settlement 5.7   5.7       57.3       57.3
Current Value 6.0   5.6                
Gross Amount of Recognized Assets     0.1                
Derivatives Available for Offset (0.3)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, February, 2028                      
Derivative [Line Items]                      
Value at Settlement 5.3           54.8        
Current Value 5.7                    
Derivatives Available for Offset (0.4)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, June, 2027                      
Derivative [Line Items]                      
Value at Settlement 6.7   6.7       69.8       69.8
Current Value 7.1   6.6                
Gross Amount of Recognized Assets     0.1                
Derivatives Available for Offset (0.4)                    
Open Forward Foreign Currency Contract, Identifier [Axis]: JP Morgan Chase Bank ,SEK, October, 2025                      
Derivative [Line Items]                      
Value at Settlement 45.4   49.5       kr 486.0       kr 529.3
Current Value 48.9   48.6                
Gross Amount of Recognized Assets     0.9                
Derivatives Available for Offset (3.5)                    
Investment, Identifier [Axis]: 3Pillar Global Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.1                    
Fair Value, ending balance 1.8 [4],[18]   1.1 [3],[17]                
Investment, Identifier [Axis]: 3Pillar Global Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[20] 117.9                    
Fair Value, ending balance 119.0 [4],[18],[21],[22]   117.9 [3],[17],[19],[20]                
Investment, Identifier [Axis]: 3Pillar Global Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.6                    
Fair Value, ending balance 7.1 [4],[24]   7.6 [3],[23]                
Investment, Identifier [Axis]: 48Forty Solutions LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [25] 148.5 0.0 0.0                
Gross Additions 3.8 [5]   184.4 [6],[25]                
Gross Reductions 0.0 [7]   (10.7) [8],[25]                
Net Realized Gain (Loss) 0.0   (0.1) [25]                
Net Change in Unrealized Appreciation (Depreciation) (16.5)   (25.1) [25]                
Fair Value, ending balance 135.8   148.5 [25]                
Investment Income 1.0 [9]   16.0 [10],[25]                
PIK Income 3.8 [9]   4.4 [10],[25]                
Fee income 0.0 [9]   0.0 [10],[25]                
Dividend and Other Income 0.0 [9]   0.0 [10],[25]                
Investment, Identifier [Axis]: 48Forty Solutions LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [25] 3.0 0.0 0.0                
Gross Additions 0.0 [5]   8.8 [6],[25]                
Gross Reductions (0.6) [7]   (4.2) [8],[25]                
Net Realized Gain (Loss) 0.0   0.0 [25]                
Net Change in Unrealized Appreciation (Depreciation) (0.9)   (1.6) [25]                
Fair Value, ending balance 1.5   3.0 [25]                
Investment Income 0.1 [9]   1.0 [10],[25]                
PIK Income 0.0 [9]   0.0 [10],[25]                
Fee income 0.0 [9]   0.0 [10],[25]                
Dividend and Other Income 0.0 [9]   0.0 [10],[25]                
Investment, Identifier [Axis]: 48Forty Solutions LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[26],[27],[28] 148.5                    
Fair Value, ending balance 135.8 [4],[18],[29]   148.5 [3],[17],[19],[26],[27],[28]                
Investment, Identifier [Axis]: 48Forty Solutions LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 3.9                    
Fair Value, ending balance 3.1 [4],[18],[29]   3.9 [3],[17],[26]                
Investment, Identifier [Axis]: 48Forty Solutions LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[26] 5.2                    
Fair Value, ending balance 5.0 [4],[24],[29]   5.2 [3],[23],[26]                
Investment, Identifier [Axis]: 48Forty Solutions LLC, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: 48Forty Solutions LLC, Common Stock, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[26],[27],[28],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[29],[31]   0.0 [3],[17],[19],[26],[27],[28],[30]                
Investment, Identifier [Axis]: 801 5th Ave, Seattle, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: 801 5th Ave, Seattle, ABF Equity, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[35]   0.0 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: 801 5th Ave, Seattle, Structure Mezzanine                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 54.5 52.7 52.7                
Gross Additions 0.1 [11]   2.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.9   (0.2)                
Fair Value, ending balance 55.5   54.5                
Investment Income 1.5 [15]   5.1 [16]                
PIK Income 0.5 [15]   1.8 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: 801 5th Ave, Seattle, Structured Mezzanine, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 54.5                    
Fair Value, ending balance 55.5 [4],[18],[34],[35]   54.5 [3],[17],[32],[33]                
Investment, Identifier [Axis]: ATX Networks Corp                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 32.9 32.9 32.9                
Gross Additions [12]     1.9                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (1.9)                
Fair Value, ending balance     32.9                
Investment Income [16]     0.0                
PIK Income [16]     0.7                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: ATX Networks Corp 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 65.1 65.1                
Gross Additions [12]     36.3                
Gross Reductions [14]     (101.4)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [16]     1.8                
PIK Income [16]     5.8                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: ATX Networks Corp 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 37.0 0.0 0.0                
Gross Additions 1.1 [11]   36.4 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   0.6                
Fair Value, ending balance 38.0   37.0                
Investment Income (0.7) [15]   0.0 [16]                
PIK Income 1.0 [15]   0.8 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 15.3 0.0 0.0                
Gross Additions 0.4 [11]   15.3 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 15.7   15.3                
Investment Income 0.1 [15]   0.0 [16]                
PIK Income 0.4 [15]   1.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 50.6 0.0 0.0                
Gross Additions 1.5 [11]   50.6 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 52.1   50.6                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 1.4 [15]   4.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 32.9                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 2.7                    
Fair Value, ending balance 35.6   32.9                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: ATX Networks Corp, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 15.3                    
Fair Value, ending balance 15.7 [4],[18],[34],[35]   15.3 [3],[17],[32],[33]                
Investment, Identifier [Axis]: ATX Networks Corp, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33],[36] 50.6                    
Fair Value, ending balance 52.1 [4],[18],[34],[35],[37]   50.6 [3],[17],[32],[33],[36]                
Investment, Identifier [Axis]: ATX Networks Corp, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33],[36] 37.0                    
Fair Value, ending balance 38.0 [4],[18],[34],[35],[37]   37.0 [3],[17],[32],[33],[36]                
Investment, Identifier [Axis]: ATX Networks Corp, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[32],[33] 5.4                    
Fair Value, ending balance 5.4 [4],[24],[34],[35]   5.4 [3],[23],[32],[33]                
Investment, Identifier [Axis]: ATX Networks Corp, Capital Goods 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33],[36],[38] 32.9                    
Fair Value, ending balance 35.6 [4],[18],[31],[34],[35],[37],[39]   32.9 [3],[17],[30],[32],[33],[36],[38]                
Investment, Identifier [Axis]: ATX Networks Corp, Class B-1 Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 2.5 2.5                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (2.5)                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp, Class B-1 Common Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[35]   0.0 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: ATX Networks Corp, Class B-2 Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.8 0.8                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (0.8)                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp, Class B-2 Common Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[35]   0.0 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: ATX Networks Corp, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 25.9 25.9                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (25.9)                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: ATX Networks Corp, Common Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33],[36] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[34],[35],[37]   0.0 [3],[17],[30],[32],[33],[36]                
Investment, Identifier [Axis]: Aareon AG, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 61.6                    
Fair Value, ending balance 29.2 [4],[18],[35]   61.6 [3],[17],[33]                
Investment, Identifier [Axis]: Aareon AG, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 15.1                    
Fair Value, ending balance 15.2 [4],[24],[35]   15.1 [3],[23],[33]                
Investment, Identifier [Axis]: Abacus JV, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 24.6 48.5 48.5                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (27.0) [13]   (11.3) [14]                
Net Realized Gain (Loss) 0.7   0.3                
Net Change in Unrealized Appreciation (Depreciation) 2.2   (12.9)                
Fair Value, ending balance 0.5   24.6                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Abacus JV, ABF Equity, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 24.6                    
Fair Value, ending balance 0.5 [4],[18],[31],[34],[35]   24.6 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Accelerator Investments Aggregator LP, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.9                    
Gross Additions [5] 0.0                    
Gross Reductions [7] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 0.9   0.9                
Investment Income [9] 0.0                    
PIK Income [9] 0.0                    
Fee income [9] 0.0                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Accelerator Investments Aggregator LP, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30],[33] 0.9                    
Fair Value, ending balance 0.9 [4],[18],[29],[31],[35]   0.9 [3],[17],[26],[30],[33]                
Investment, Identifier [Axis]: Accelerator Investments Aggregator LP, Private Equity4)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [25] 0.9 2.5 2.5                
Gross Additions [6],[25]     0.0                
Gross Reductions [8],[25]     (1.6)                
Net Realized Gain (Loss) [25]     (0.1)                
Net Change in Unrealized Appreciation (Depreciation) [25]     0.1                
Fair Value, ending balance [25]     0.9                
Investment Income [10],[25]     0.0                
PIK Income [10],[25]     0.0                
Fee income [10],[25]     0.0                
Dividend and Other Income [10],[25]     0.0                
Investment, Identifier [Axis]: Accuride Corp                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 4.2                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 3.4                    
Fair Value, ending balance 7.6   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Accuride Corp, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[21],[34] 7.6                    
Investment, Identifier [Axis]: Accuride Corp, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[40] 0.7                    
Fair Value, ending balance [3],[19],[40]     0.7                
Investment, Identifier [Axis]: Accuride Corp, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19] 2.6                    
Fair Value, ending balance [3],[19]     2.6                
Investment, Identifier [Axis]: Accuride Corp, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[30],[38] 2.1                    
Fair Value, ending balance [3],[19],[30],[38]     2.1                
Investment, Identifier [Axis]: Accuride Corp, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[40] 0.4                    
Fair Value, ending balance [3],[23],[40]     0.4                
Investment, Identifier [Axis]: Accuride Corp, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 0.0   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Accuride Corp, Common Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[21],[31],[34] 0.0                    
Investment, Identifier [Axis]: Accuride Corp, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 0.0   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Accuride Corp, Preferred Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[21],[31],[34] 0.0                    
Investment, Identifier [Axis]: Advanced Dermatology & Cosmetic Surgery, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.3                    
Fair Value, ending balance 0.8 [4],[18]   0.3 [3],[17]                
Investment, Identifier [Axis]: Advanced Dermatology & Cosmetic Surgery, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[28],[41] 45.5                    
Fair Value, ending balance 45.3 [4],[18],[42],[43],[44]   45.5 [3],[17],[28],[41]                
Investment, Identifier [Axis]: Advanced Dermatology & Cosmetic Surgery, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.3                    
Fair Value, ending balance 2.7 [4],[24]   3.3 [3],[23]                
Investment, Identifier [Axis]: Advania Sverige AB, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 64.4                    
Fair Value, ending balance 5.4 [4],[18],[35],[45]   64.4 [3],[17],[33]                
Investment, Identifier [Axis]: Advania Sverige AB, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 14.7                    
Fair Value, ending balance 66.3 [4],[18],[35]   14.7 [3],[17],[33]                
Investment, Identifier [Axis]: Advania Sverige AB, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33],[46] 5.2                    
Fair Value, ending balance 16.0 [4],[18],[35]   5.2 [3],[17],[33],[46]                
Investment, Identifier [Axis]: Affordable Care Inc 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 35.2 35.6 35.6                
Gross Additions 1.5 [5]   6.6 [6]                
Gross Reductions (1.1) [7]   (7.4) [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.2   0.4                
Fair Value, ending balance 35.8   35.2                
Investment Income 0.7 [9]   4.2 [10]                
PIK Income 0.3 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Affordable Care Inc 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 22.2 7.3 7.3                
Gross Additions 0.2 [5]   14.9 [6]                
Gross Reductions 0.0 [7]   (0.1) [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.1                
Fair Value, ending balance 22.4   22.2                
Investment Income 0.4 [9]   1.8 [10]                
PIK Income 0.2 [9]   0.0 [10]                
Fee income 0.0 [9]   0.1 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Affordable Care Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 1.3                    
Fair Value, ending balance 1.5 [4],[18],[29]   1.3 [3],[17],[26]                
Investment, Identifier [Axis]: Affordable Care Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[41] 56.2                    
Fair Value, ending balance 56.7 [4],[18],[29],[42],[44]   56.2 [3],[17],[26],[41]                
Investment, Identifier [Axis]: Affordable Care Inc, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[26] 11.5                    
Fair Value, ending balance 11.3 [4],[24],[29]   11.5 [3],[23],[26]                
Investment, Identifier [Axis]: Affordable Care Inc, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 73.1 50.0 50.0                
Gross Additions 1.9 [5]   19.8 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   3.3                
Fair Value, ending balance 74.9   73.1                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 2.0 [9]   6.4 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Affordable Care Inc, Preferred Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 73.1                    
Fair Value, ending balance 74.9 [4],[18],[29]   73.1 [3],[17],[26]                
Investment, Identifier [Axis]: Alacrity Solutions Group LLC                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 3.4                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 3.4   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 10.2                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.1                    
Fair Value, ending balance 10.3   0.0                
Investment Income [15] 0.1                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 0.1                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 0.1   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 1.9                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (0.1)                    
Fair Value, ending balance 1.8   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Common Stock, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[31],[34],[44] 1.8                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[38] 7.7                    
Fair Value, ending balance 10.3 [4],[18],[34],[44]   7.7 [3],[17],[30],[38]                
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[38],[41] 8.5                    
Fair Value, ending balance 0.1 [4],[18],[34],[44]   8.5 [3],[30],[38],[41]                
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[34] 1.7                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Insurance 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[34] 2.3                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Insurance 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[34],[44] 3.4                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Preferred Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 2.3                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 2.3   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Alacrity Solutions Group LLC, Preferred Equity, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[34],[44] 2.3                    
Investment, Identifier [Axis]: Alera Group Intermediate Holdings Inc, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 31.1                    
Fair Value, ending balance 31.0 [4],[18],[42],[44]   31.1 [3],[17],[41]                
Investment, Identifier [Axis]: Alera Group Intermediate Holdings Inc, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 7.3                    
Fair Value, ending balance 7.6 [4],[18],[42]   7.3 [3],[17]                
Investment, Identifier [Axis]: Alera Group Intermediate Holdings Inc, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.4                    
Fair Value, ending balance [3],[23]     0.4                
Investment, Identifier [Axis]: Alpha Financial Markets Consulting PLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 10.2                    
Fair Value, ending balance 10.3 [4],[18],[35],[42]   10.2 [3],[17],[33]                
Investment, Identifier [Axis]: Alpha Financial Markets Consulting PLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 4.8                    
Fair Value, ending balance 5.8 [4],[24],[35]   4.8 [3],[17],[33]                
Investment, Identifier [Axis]: Alpha Financial Markets Consulting PLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 10.8                    
Fair Value, ending balance [3],[17],[33]     10.8                
Investment, Identifier [Axis]: Alpha Financial Markets Consulting PLC, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 5.8                    
Fair Value, ending balance [3],[23],[33]     5.8                
Investment, Identifier [Axis]: Altavair AirFinance, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 128.2                    
Gross Additions [5] 0.0                    
Gross Reductions [7] (1.6)                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (0.1)                    
Fair Value, ending balance 126.5   128.2                
Investment Income [9] 0.0                    
PIK Income [9] 0.0                    
Fee income [9] 0.0                    
Dividend and Other Income [9] 8.9                    
Investment, Identifier [Axis]: Altavair AirFinance, ABF Equity, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[33] 128.2                    
Fair Value, ending balance 126.5 [4],[18],[29],[35]   128.2 [3],[17],[26],[33]                
Investment, Identifier [Axis]: Altavair AirFinance, Private Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 128.2 133.9 133.9                
Gross Additions [6]     0.0                
Gross Reductions [8]     (7.4)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     1.7                
Fair Value, ending balance     128.2                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     15.5                
Investment, Identifier [Axis]: Altitude II IRL WH Borrower DAC, Revolver, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 6.1                    
Fair Value, ending balance 6.3 [4],[18],[35]   6.1 [3],[17],[33]                
Investment, Identifier [Axis]: Altitude II IRL WH Borrower DAC, Revolver, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 3.7                    
Fair Value, ending balance 3.5 [4],[24],[35]   3.7 [3],[23],[33]                
Investment, Identifier [Axis]: American Vision Partners, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 5.0                    
Fair Value, ending balance 3.9 [4],[18]   5.0 [3],[17]                
Investment, Identifier [Axis]: American Vision Partners, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20] 89.9                    
Fair Value, ending balance 52.2 [4],[18],[22],[42]   89.9 [3],[17],[20]                
Investment, Identifier [Axis]: American Vision Partners, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.8                    
Fair Value, ending balance 37.8 [4],[18],[42]   2.8 [3],[23]                
Investment, Identifier [Axis]: American Vision Partners, Health Care Equipment & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 3.9                    
Investment, Identifier [Axis]: American Vision Partners, Private Equity, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 2.0                    
Fair Value, ending balance 2.0 [4],[18],[31]   2.0 [3],[17],[30]                
Investment, Identifier [Axis]: Amerivet Partners Management Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 67.6                    
Fair Value, ending balance 67.5 [4],[18],[42]   67.6 [3],[17]                
Investment, Identifier [Axis]: Amerivet Partners Management Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.4                    
Fair Value, ending balance 8.4 [4],[24]   8.4 [3],[23]                
Investment, Identifier [Axis]: Amerivet Partners Management Inc, Preferred Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 14.1                    
Fair Value, ending balance 14.1 [4],[18]   14.1 [3],[17]                
Investment, Identifier [Axis]: Apex Group Limited, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[33],[41],[46] 2.5                    
Fair Value, ending balance 2.4 [4],[35],[44],[45]   2.5 [3],[33],[41],[46]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 3.5                    
Fair Value, ending balance 4.3 [4],[18]   3.5 [3],[17]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 9.0                    
Fair Value, ending balance 20.2 [4],[18]   9.0 [3],[17]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 93.8                    
Fair Value, ending balance 95.3 [4],[18],[42]   93.8 [3],[17]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.6                    
Fair Value, ending balance 0.8 [4],[24]   1.6 [3],[23]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 22.2                    
Fair Value, ending balance 11.5 [4],[24]   22.2 [3],[23]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 6                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 7.3                    
Fair Value, ending balance 24.3 [4],[18]   7.3 [3],[17]                
Investment, Identifier [Axis]: Apex Service Partners LLC, Commercial & Professional Services 7                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 15.0                    
Fair Value, ending balance [3],[17]     15.0                
Investment, Identifier [Axis]: Arcfield Acquisition Corp, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.0                    
Fair Value, ending balance 6.0 [4],[24]   6.0 [3],[23]                
Investment, Identifier [Axis]: Arcos LLC/VA, Preferred Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 22.2                    
Fair Value, ending balance 22.5 [4],[18]   22.2 [3],[17]                
Investment, Identifier [Axis]: Arcos LLC/VA, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[41] 11.9                    
Fair Value, ending balance 12.1 [4],[44]   11.9 [3],[41]                
Investment, Identifier [Axis]: Arcos LLC/VA, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.2                    
Fair Value, ending balance 4.2 [4],[24]   4.2 [3],[23]                
Investment, Identifier [Axis]: Area Wide Protective Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 19.2                    
Fair Value, ending balance 19.2 [4],[18],[47]   19.2 [3],[17],[27]                
Investment, Identifier [Axis]: Area Wide Protective Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 12.1                    
Fair Value, ending balance 12.1 [4],[24]   12.1 [3],[23]                
Investment, Identifier [Axis]: Arena Energy LP, Warrants, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.1                    
Fair Value, ending balance [3],[17]     0.1                
Investment, Identifier [Axis]: Arrotex Australia Group Pty Ltd, Pharmaceuticals, Biotechnology & Life Sciences                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 6.6                    
Investment, Identifier [Axis]: Arrotex Australia Group Pty Ltd, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 4.3                    
Fair Value, ending balance [3],[17],[33]     4.3                
Investment, Identifier [Axis]: Arrotex Australia Group Pty Ltd, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.4                    
Fair Value, ending balance [3],[23],[33]     2.4                
Investment, Identifier [Axis]: Ascent Resources Utica Holdings LLC / ARU Finance Corp, Common Stock, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[48],[49] 2.9                    
Fair Value, ending balance 3.2 [4],[31],[50],[51]   2.9 [3],[30],[48],[49]                
Investment, Identifier [Axis]: Ascent Resources Utica Holdings LLC / ARU Finance Corp, Trade Claim, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[48],[49] 24.5                    
Fair Value, ending balance 27.3 [4],[31],[50],[51]   24.5 [3],[30],[48],[49]                
Investment, Identifier [Axis]: Australis Maritime II, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 19.8 12.2 12.2                
Gross Additions 0.0 [11]   10.4 [12]                
Gross Reductions (3.1) [13]   (1.6) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.2)   (1.2)                
Fair Value, ending balance 16.5   19.8                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.6 [15]   2.2 [16]                
Investment, Identifier [Axis]: Australis Maritime II, ABF Equity, Transportation                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 19.8                    
Fair Value, ending balance 16.5 [4],[18],[34],[35]   19.8 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Australis Maritime, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 11.3 35.8 35.8                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (0.3) [13]   (23.8) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   (0.7)                
Fair Value, ending balance 11.1   11.3                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.3 [16]                
Investment, Identifier [Axis]: Australis Maritime, Common Stock, Transportation                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 11.3                    
Fair Value, ending balance 11.1 [4],[18],[34],[35]   11.3 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Auxilior Capital Partners Inc, Preferred Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 16.9                    
Fair Value, ending balance 18.4 [4],[18]   16.9 [3],[17]                
Investment, Identifier [Axis]: Avenue One PropCo, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 10.2                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (1.3)                    
Fair Value, ending balance 8.9   10.2                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Avenue One PropCo, ABF Equity 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 38.8 38.8                
Gross Additions [12]     0.0                
Gross Reductions [14]     (37.9)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (0.9)                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Avenue One PropCo, ABF Equity 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 10.2 0.0 0.0                
Gross Additions [12]     10.3                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (0.1)                
Fair Value, ending balance     10.2                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Avenue One PropCo, ABF Equity, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 10.2                    
Fair Value, ending balance 8.9 [4],[18],[31],[34],[35]   10.2 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Avenue One PropCo, Term Loan                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 32.3 0.0 0.0                
Gross Additions 0.6 [11]   32.3 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 32.9   32.3                
Investment Income 0.0 [15]   0.1 [16]                
PIK Income 0.6 [15]   1.7 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Avenue One PropCo, Term Loan, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 32.3                    
Fair Value, ending balance 32.9 [4],[18],[34],[35]   32.3 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Avetta LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 14.9                    
Fair Value, ending balance 8.4 [4],[42]   14.9 [3],[17]                
Investment, Identifier [Axis]: Avetta LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.6                    
Fair Value, ending balance 2.6 [4],[24]   2.6 [3],[23]                
Investment, Identifier [Axis]: Avetta LLC, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.7                    
Fair Value, ending balance 3.7 [4],[24]   3.7 [3],[23]                
Investment, Identifier [Axis]: Avida Holding AB, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 60.4 42.9 42.9                
Gross Additions 0.0 [11]   25.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.9)   (7.5)                
Fair Value, ending balance 59.5   60.4                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Avida Holding AB, Common Stock, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 60.4                    
Fair Value, ending balance 59.5 [4],[18],[31],[34],[35]   60.4 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Avida Holding AB, Subordinated Bond                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1.3 1.5 1.5                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.2   (0.2)                
Fair Value, ending balance 1.5   1.3                
Investment Income 0.0 [15]   0.2 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Avida Holding AB, Subordinated Bond, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 1.3                    
Fair Value, ending balance 1.5 [4],[18],[34],[35]   1.3 [3],[17],[32],[33]                
Investment, Identifier [Axis]: BDO USA PA, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 28.1                    
Fair Value, ending balance 28.1 [4],[18],[42]   28.1 [3],[17]                
Investment, Identifier [Axis]: BGB Group LLC, Media & Entertainment 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[20],[27],[28],[41] 107.7                    
Fair Value, ending balance 107.7 [4],[21],[22],[42],[43],[44],[47]   107.7 [3],[19],[20],[27],[28],[41]                
Investment, Identifier [Axis]: BGB Group LLC, Media & Entertainment 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.3                    
Fair Value, ending balance 7.4 [4],[24]   7.3 [3],[23]                
Investment, Identifier [Axis]: BGB Group LLC, Media & Entertainment 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 19.7                    
Fair Value, ending balance 19.8 [4],[24]   19.7 [3],[23]                
Investment, Identifier [Axis]: Bankers Healthcare Group LLC, Term Loan, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 8.6                    
Fair Value, ending balance 8.6 [4],[18],[35]   8.6 [3],[17],[33]                
Investment, Identifier [Axis]: Bausch Health Cos Inc, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 60.0                    
Fair Value, ending balance 60.0 [4],[18],[35]   60.0 [3],[17],[33]                
Investment, Identifier [Axis]: Bausch Health Cos Inc, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 60.0                    
Fair Value, ending balance 60.0 [4],[24],[35]   60.0 [3],[23],[33]                
Investment, Identifier [Axis]: Belk Inc                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 29.5                    
Gross Additions [5] 0.0                    
Gross Reductions [7] (1.8)                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.1                    
Fair Value, ending balance 27.8   29.5                
Investment Income [9] 1.0                    
PIK Income [9] 0.0                    
Fee income [9] 0.0                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Belk Inc 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 13.2 13.2                
Gross Additions [6]     0.0                
Gross Reductions [8]     (16.7)                
Net Realized Gain (Loss)     (18.9)                
Net Change in Unrealized Appreciation (Depreciation)     22.4                
Fair Value, ending balance     0.0                
Investment Income [10]     (0.9)                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 20.0 20.0                
Gross Additions [6]     0.0                
Gross Reductions [8]     (21.9)                
Net Realized Gain (Loss)     0.1                
Net Change in Unrealized Appreciation (Depreciation)     1.8                
Fair Value, ending balance     0.0                
Investment Income [10]     1.9                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 29.5 0.0 0.0                
Gross Additions [6]     30.0                
Gross Reductions [8]     (0.6)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.1                
Fair Value, ending balance     29.5                
Investment Income [10]     2.0                
PIK Income [10]     0.0                
Fee income [10]     0.9                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [6]     0.0                
Gross Reductions [8]     (0.7)                
Net Realized Gain (Loss)     (3.5)                
Net Change in Unrealized Appreciation (Depreciation)     4.2                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 27.1                    
Gross Additions [5] 4.2                    
Gross Reductions [7] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 4.2                    
Fair Value, ending balance 35.5   27.1                
Investment Income [9] 0.0                    
PIK Income [9] 0.0                    
Fee income [9] 0.0                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Belk Inc, Common Stock 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [6]     0.0                
Gross Reductions [8]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc, Common Stock 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 27.1 0.0 0.0                
Gross Additions [6]     17.6                
Gross Reductions [8]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     9.5                
Fair Value, ending balance     27.1                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Belk Inc, Common Stock, Consumer Discretionary Distribution & Retail                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 27.1                    
Fair Value, ending balance 35.5 [4],[18],[29],[31]   27.1 [3],[17],[30],[32]                
Investment, Identifier [Axis]: Belk Inc, Consumer Discretionary Distribution & Retail                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 29.5                    
Fair Value, ending balance 27.8 [4],[18],[29]   29.5 [3],[17],[32]                
Investment, Identifier [Axis]: Bloom Fresh International Limited, Food, Beverage & Tobacco                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 7.7                    
Fair Value, ending balance 8.0 [4],[18],[35]   7.7 [3],[17],[33]                
Investment, Identifier [Axis]: Bonterra LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[42],[43],[47] 117.3                    
Investment, Identifier [Axis]: Bonterra LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18] 2.8                    
Investment, Identifier [Axis]: Bonterra LLC, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 16.9                    
Investment, Identifier [Axis]: Bonterra LLC, Software & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 14.2                    
Investment, Identifier [Axis]: Borden (New Dairy Opco), Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 18.4                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.1                    
Fair Value, ending balance 18.5   18.4                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Borden (New Dairy Opco), Common Stock 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [25] 0.0 11.2 11.2                
Gross Additions [6],[25]     0.0                
Gross Reductions [8],[25]     (4.9)                
Net Realized Gain (Loss) [25]     0.0                
Net Change in Unrealized Appreciation (Depreciation) [25]     (6.3)                
Fair Value, ending balance [25]     0.0                
Investment Income [10],[25]     0.0                
PIK Income [10],[25]     0.0                
Fee income [10],[25]     0.0                
Dividend and Other Income [10],[25]     0.0                
Investment, Identifier [Axis]: Borden (New Dairy Opco), Common Stock 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 18.4 0.0 0.0                
Gross Additions [12]     4.9                
Gross Reductions [14]     (5.3)                
Net Realized Gain (Loss)     0.4                
Net Change in Unrealized Appreciation (Depreciation)     18.4                
Fair Value, ending balance     18.4                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Borden (New Dairy Opco), Common Stock, Food, Beverage & Tobacco                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[32],[48],[52] 18.4                    
Fair Value, ending balance 18.5 [4],[31],[34],[50],[53]   18.4 [3],[30],[32],[48],[52]                
Investment, Identifier [Axis]: Bowery Farming Inc, Common Stock, Food, Beverage & Tobacco                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31]   0.0 [3],[17],[30]                
Investment, Identifier [Axis]: Bowery Farming Inc, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[38] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[39]   0.0 [3],[17],[30],[38]                
Investment, Identifier [Axis]: Bowery Farming Inc, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 7.2                    
Fair Value, ending balance 3.7 [4],[18],[31]   7.2 [3],[17],[30]                
Investment, Identifier [Axis]: Bowery Farming Inc, Food, Beverage & Tobacco 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 2.8                    
Fair Value, ending balance 1.4 [4],[18],[31]   2.8 [3],[17],[30]                
Investment, Identifier [Axis]: Bowery Farming Inc, Warrant, Food, Beverage & Tobacco                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31]   0.0 [3],[17],[30]                
Investment, Identifier [Axis]: Bowery Farming Inc, Warrants, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31]   0.0 [3],[17],[30]                
Investment, Identifier [Axis]: Bowery Farming Inc, Warrants, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31]   0.0 [3],[17],[30]                
Investment, Identifier [Axis]: Byrider Finance LLC, ABF Equity, Automobiles & Components                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[54] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[55]   0.0 [3],[17],[30],[54]                
Investment, Identifier [Axis]: CDS US Intermediate Holdings Inc, Warrant, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 14.9                    
Fair Value, ending balance 14.9 [4],[18],[31],[35]   14.9 [3],[17],[30],[33]                
Investment, Identifier [Axis]: CFC Underwriting Ltd, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 5.7                    
Fair Value, ending balance 5.7 [4],[24],[35]   5.7 [3],[23],[33]                
Investment, Identifier [Axis]: CLEAResult Consulting Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 18.0                    
Fair Value, ending balance 18.3 [4],[18],[42],[47]   18.0 [3],[17],[27]                
Investment, Identifier [Axis]: CLEAResult Consulting Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.4                    
Fair Value, ending balance 1.6 [4],[18]   1.4 [3],[17]                
Investment, Identifier [Axis]: CLEAResult Consulting Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.5                    
Fair Value, ending balance 4.6 [4],[24]   4.5 [3],[23]                
Investment, Identifier [Axis]: CLEAResult Consulting Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.7                    
Fair Value, ending balance 1.5 [4],[24]   1.7 [3],[23]                
Investment, Identifier [Axis]: CSafe Global, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28] 88.6                    
Fair Value, ending balance 88.3 [4],[18],[21],[43],[47]   88.6 [3],[17],[19],[27],[28]                
Investment, Identifier [Axis]: CSafe Global, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 19.5                    
Fair Value, ending balance 11.2 [4],[18]   19.5 [3],[17]                
Investment, Identifier [Axis]: CSafe Global, Transportation 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 8.1                    
Fair Value, ending balance 20.0 [4],[18]   8.1 [3],[17]                
Investment, Identifier [Axis]: CSafe Global, Transportation 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.5                    
Fair Value, ending balance 0.3 [4],[24]   3.5 [3],[23]                
Investment, Identifier [Axis]: Cadence Education LLC, Consumer Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 4.6                    
Fair Value, ending balance 5.8 [4],[18]   4.6 [3],[17]                
Investment, Identifier [Axis]: Cadence Education LLC, Consumer Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.5                    
Fair Value, ending balance 8.5 [4],[24]   8.5 [3],[23]                
Investment, Identifier [Axis]: Cadence Education LLC, Consumer Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 9.8                    
Fair Value, ending balance 8.7 [4],[24]   9.8 [3],[23]                
Investment, Identifier [Axis]: Callodine Commercial Finance LLC, 2L Term Loan A, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 88.4                    
Fair Value, ending balance 88.4 [4],[18]   88.4 [3],[17]                
Investment, Identifier [Axis]: Callodine Commercial Finance LLC, 2L Term Loan B, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 12.0                    
Fair Value, ending balance 12.0 [4],[18]   12.0 [3],[17]                
Investment, Identifier [Axis]: Callodine Commercial Finance LLC, 2L Term Loan B, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 36.1                    
Fair Value, ending balance 36.1 [4],[24]   36.1 [3],[23]                
Investment, Identifier [Axis]: Cambrex Corp, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[42],[47] 30.7                    
Investment, Identifier [Axis]: Cambrex Corp, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 9.4                    
Investment, Identifier [Axis]: Cambrex Corp, Pharmaceuticals, Biotechnology & Life Sciences 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 8.2                    
Investment, Identifier [Axis]: Capital Automotive LP, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 32.9 32.4 32.4                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (17.3) [13]   (1.1) [14]                
Net Realized Gain (Loss) 6.8   0.0                
Net Change in Unrealized Appreciation (Depreciation) (5.4)   1.6                
Fair Value, ending balance 17.0   32.9                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.5 [15]   2.9 [16]                
Investment, Identifier [Axis]: Capital Automotive LP, ABF Equity, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 32.9                    
Fair Value, ending balance 17.0 [4],[18],[34],[35]   32.9 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Capital Automotive LP, Structured Mezzanine                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 40.1 41.5 41.5                
Gross Additions 0.0 [11]   0.1 [12]                
Gross Reductions (20.4) [13]   (1.4) [14]                
Net Realized Gain (Loss) 0.1   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   (0.1)                
Fair Value, ending balance 19.7   40.1                
Investment Income 1.1 [15]   4.6 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Capital Automotive LP, Structured Mezzanine, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 40.1                    
Fair Value, ending balance 19.7 [4],[18],[34],[35]   40.1 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Carrier Fire Protection, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 9.7                    
Fair Value, ending balance 0.4 [4],[18]   9.7 [3],[17]                
Investment, Identifier [Axis]: Carrier Fire Protection, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.3                    
Fair Value, ending balance 9.8 [4],[18],[42]   0.3 [3],[17]                
Investment, Identifier [Axis]: Carrier Fire Protection, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 2.5                    
Fair Value, ending balance 2.6 [4],[18]   2.5 [3],[17]                
Investment, Identifier [Axis]: Carrier Fire Protection, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.6                    
Fair Value, ending balance 2.1 [4],[24]   2.6 [3],[23]                
Investment, Identifier [Axis]: Carrier Fire Protection, Commercial & Professional Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.3                    
Fair Value, ending balance 2.6 [4],[24]   2.3 [3],[23]                
Investment, Identifier [Axis]: Cengage Learning, Inc, Common Stock, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 4.3                    
Fair Value, ending balance 4.4 [4],[18],[31]   4.3 [3],[17],[30]                
Investment, Identifier [Axis]: Circana Group (f.k.a. NPD Group), Consumer Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.2                    
Fair Value, ending balance 0.1 [4],[18]   0.2 [3],[17]                
Investment, Identifier [Axis]: Circana Group (f.k.a. NPD Group), Consumer Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 19.8                    
Fair Value, ending balance 19.8 [4],[18],[42],[44]   19.8 [3],[17],[41]                
Investment, Identifier [Axis]: Circana Group (f.k.a. NPD Group), Consumer Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.8                    
Fair Value, ending balance 0.9 [4],[24]   0.8 [3],[23]                
Investment, Identifier [Axis]: Civica Group Ltd, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 3.1                    
Fair Value, ending balance 3.2 [4],[18],[35]   3.1 [3],[17],[33]                
Investment, Identifier [Axis]: Civica Group Ltd, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 6.4                    
Fair Value, ending balance 6.4 [4],[24],[35]   6.4 [3],[23],[33]                
Investment, Identifier [Axis]: Civica Group Ltd, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 4.6                    
Fair Value, ending balance 4.6 [4],[24],[35]   4.6 [3],[23],[33]                
Investment, Identifier [Axis]: Clarience Technologies LLC, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28] 160.5                    
Fair Value, ending balance 1.4 [4],[18]   160.5 [3],[17],[19],[27],[28]                
Investment, Identifier [Axis]: Clarience Technologies LLC, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 21.7                    
Fair Value, ending balance 174.0 [4],[18],[21],[43],[47]   21.7 [3],[23]                
Investment, Identifier [Axis]: Clarience Technologies LLC, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 21.9                    
Fair Value, ending balance 20.2 [4],[24]   21.9 [3],[23]                
Investment, Identifier [Axis]: Clarience Technologies LLC, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 7.9                    
Investment, Identifier [Axis]: Colosseum AG, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 12.7                    
Investment, Identifier [Axis]: Colosseum Dental Group, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 11.7                    
Fair Value, ending balance [3],[17],[33]     11.7                
Investment, Identifier [Axis]: Community Brands Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[28] 39.9                    
Fair Value, ending balance 42.3 [4],[18],[43]   39.9 [3],[19],[28]                
Investment, Identifier [Axis]: Community Brands Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 15.7                    
Fair Value, ending balance 4.4 [4],[24]   15.7 [3],[23]                
Investment, Identifier [Axis]: Community Brands Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 8.8                    
Investment, Identifier [Axis]: Consilium Safety Group AB, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 10.6                    
Investment, Identifier [Axis]: Consilium Safety Group AB, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 25.8                    
Fair Value, ending balance [3],[17],[33]     25.8                
Investment, Identifier [Axis]: Consilium Safety Group AB, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 10.1                    
Fair Value, ending balance [3],[23],[33]     10.1                
Investment, Identifier [Axis]: Constellis Holdings LLC                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.0                    
Gross Additions [5] 0.5                    
Gross Reductions [7] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 7.5   7.0                
Investment Income [9] 0.3                    
PIK Income [9] 0.2                    
Fee income [9] 0.0                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Constellis Holdings LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 15.1 15.1                
Gross Additions [6]     0.2                
Gross Reductions [8]     (15.1)                
Net Realized Gain (Loss)     0.3                
Net Change in Unrealized Appreciation (Depreciation)     (0.5)                
Fair Value, ending balance     0.0                
Investment Income [10]     1.6                
PIK Income [10]     0.0                
Fee income [10]     0.1                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Constellis Holdings LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 9.0 9.0                
Gross Additions [6]     0.3                
Gross Reductions [8]     (9.9)                
Net Realized Gain (Loss)     (3.5)                
Net Change in Unrealized Appreciation (Depreciation)     4.1                
Fair Value, ending balance     0.0                
Investment Income [10]     1.7                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Constellis Holdings LLC 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.0 0.0 0.0                
Gross Additions [6]     6.8                
Gross Reductions [8]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.2                
Fair Value, ending balance     7.0                
Investment Income [10]     0.1                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Constellis Holdings LLC, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 7.0                    
Fair Value, ending balance 7.5 [4],[18],[29]   7.0 [3],[17],[26]                
Investment, Identifier [Axis]: Constellis Holdings LLC, Preferred Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 3.4 0.0 0.0                
Gross Additions 0.0 [5]   3.2 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (1.0)   0.2                
Fair Value, ending balance 2.4   3.4                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Constellis Holdings LLC, Preferred Equity, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[29],[31] 2.4                    
Investment, Identifier [Axis]: Constellis Holdings LLC, Preferred Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30] 3.4                    
Fair Value, ending balance [3],[17],[26],[30]     3.4                
Investment, Identifier [Axis]: Constellis Holdings LLC, Private Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Constellis Holdings LLC, Private Equity, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[27],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[29],[31],[47]   0.0 [3],[17],[26],[27],[30]                
Investment, Identifier [Axis]: Corsearch Intermediate Inc, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 30.1                    
Fair Value, ending balance 30.1 [4],[18],[42],[44]   30.1 [3],[17],[41]                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 3.5                    
Fair Value, ending balance [3],[17],[33]     3.5                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 1.6                    
Fair Value, ending balance [3],[17],[33]     1.6                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 2.2                    
Fair Value, ending balance [3],[17],[33]     2.2                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 8.6                    
Fair Value, ending balance [3],[23],[33]     8.6                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 1.4                    
Fair Value, ending balance [3],[23],[33]     1.4                
Investment, Identifier [Axis]: Covis Finco Sarl, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 6                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.1                    
Fair Value, ending balance [3],[23],[33]     2.1                
Investment, Identifier [Axis]: Credit Opportunities Partners JV, LLC                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1,363.3 1,396.9 1,396.9                
Gross Additions 297.7 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (33.6)                
Fair Value, ending balance 1,661.0   1,363.3                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 47.8 [15]   212.3 [16]                
Investment, Identifier [Axis]: Credit Opportunities Partners JV, LLC, Credit Opportunities Partners JV, LLC                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 1,363.3                    
Fair Value, ending balance 1,661.0 [4],[18],[34],[35]   1,363.3 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Cubic Corp, Preferred Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[38] 42.0                    
Fair Value, ending balance 35.4 [4],[18],[31],[39]   42.0 [3],[17],[30],[38]                
Investment, Identifier [Axis]: Cubic Corp, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 34.4                    
Fair Value, ending balance 34.0 [4],[18],[31],[39]   34.4 [3],[17]                
Investment, Identifier [Axis]: Curia Global Inc, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 62.0                    
Fair Value, ending balance 42.0 [4],[18],[35]   62.0 [3],[17],[33]                
Investment, Identifier [Axis]: Curia Global Inc, Revolver, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 21.3                    
Fair Value, ending balance 41.3 [4],[24],[35]   21.3 [3],[23],[33]                
Investment, Identifier [Axis]: DOC Generici Srl, Pharmaceuticals, Biotechnology & Life Sciences                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 12.5                    
Investment, Identifier [Axis]: DOC Generici Srl, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 12.0                    
Fair Value, ending balance [3],[17],[33]     12.0                
Investment, Identifier [Axis]: DOC Generici Srl, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.5                    
Fair Value, ending balance [3],[23],[33]     2.5                
Investment, Identifier [Axis]: DOXA Insurance Holdings LLC, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 29.5                    
Fair Value, ending balance 0.4 [4],[18]   29.5 [3],[17]                
Investment, Identifier [Axis]: DOXA Insurance Holdings LLC, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.3                    
Fair Value, ending balance 29.4 [4],[18],[42]   3.3 [3],[23]                
Investment, Identifier [Axis]: DOXA Insurance Holdings LLC, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.5                    
Fair Value, ending balance 2.9 [4],[24]   0.5 [3],[23]                
Investment, Identifier [Axis]: DOXA Insurance Holdings LLC, Insurance 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 22.8                    
Fair Value, ending balance 0.5 [4],[24]   22.8 [3],[23]                
Investment, Identifier [Axis]: DOXA Insurance Holdings LLC, Insurance 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 22.8                    
Investment, Identifier [Axis]: Dechra Pharmaceuticals Ltd, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 3.7                    
Fair Value, ending balance [3],[23],[33]     3.7                
Investment, Identifier [Axis]: Dechra Pharmaceuticals Ltd, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 3.5                    
Fair Value, ending balance [3],[23],[33]     3.5                
Investment, Identifier [Axis]: Dental Care Alliance Inc, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[28],[41] 107.3                    
Fair Value, ending balance 105.7 [4],[18],[21],[42],[43],[44]   107.3 [3],[17],[19],[28],[41]                
Investment, Identifier [Axis]: Dental365 LLC, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.5                    
Fair Value, ending balance 0.5 [4],[18]   0.5 [3],[17]                
Investment, Identifier [Axis]: Dental365 LLC, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 21.5                    
Fair Value, ending balance 21.4 [4],[18],[42],[47]   21.5 [3],[17],[27]                
Investment, Identifier [Axis]: Dental365 LLC, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 5.1                    
Fair Value, ending balance 6.7 [4],[18]   5.1 [3],[17]                
Investment, Identifier [Axis]: Dental365 LLC, Health Care Equipment & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.6                    
Fair Value, ending balance 4.6 [4],[24]   4.6 [3],[23]                
Investment, Identifier [Axis]: Dental365 LLC, Health Care Equipment & Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.6                    
Fair Value, ending balance 7.0 [4],[24]   8.6 [3],[23]                
Investment, Identifier [Axis]: Discover Financial Services, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 21.7 0.0 0.0                
Gross Additions 0.0 [11]   20.9 [12]                
Gross Reductions (1.2) [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.8                
Fair Value, ending balance 20.5   21.7                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 1.1 [15]   0.0 [16]                
Investment, Identifier [Axis]: Discover Financial Services, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 21.7                    
Fair Value, ending balance 20.5 [4],[18],[34],[35]   21.7 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Discover Financial Services, Subordinated Loan                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 38.8 0.0 0.0                
Gross Additions 0.0 [11]   38.8 [12]                
Gross Reductions (3.1) [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 35.7   38.8                
Investment Income 1.4 [15]   1.3 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Discover Financial Services, Subordinated Loan, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[34],[35] 35.7                    
Investment, Identifier [Axis]: Discover Financial Services, Subordinated Loan, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 38.8                    
Fair Value, ending balance [3],[17],[32],[33]     38.8                
Investment, Identifier [Axis]: Discover Financial Services, Subordinated Loan, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[32],[33] 0.1                    
Fair Value, ending balance [3],[23],[32],[33]     0.1                
Investment, Identifier [Axis]: Diversified Energy Co PLC, Common Stock, Energy 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[35],[50],[56] 23.9                    
Investment, Identifier [Axis]: Diversified Energy Co PLC, Common Stock, Energy 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[35],[50],[56] 2.7                    
Investment, Identifier [Axis]: Drive Revel, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 9.1                    
Fair Value, ending balance 12.4 [4],[18],[35]   9.1 [3],[17],[33]                
Investment, Identifier [Axis]: DuBois Chemicals Inc, Materials 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27],[28] 43.8                    
Fair Value, ending balance 43.9 [4],[18],[42],[43],[47]   43.8 [3],[17],[27],[28]                
Investment, Identifier [Axis]: DuBois Chemicals Inc, Materials 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 14.7                    
Fair Value, ending balance 14.7 [4],[24]   14.7 [3],[23]                
Investment, Identifier [Axis]: DuBois Chemicals Inc, Materials 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 14.7                    
Fair Value, ending balance 14.8 [4],[24]   14.7 [3],[23]                
Investment, Identifier [Axis]: Envirotainer Ltd, Transportation                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.8                    
Fair Value, ending balance 2.8 [4],[24],[35]   2.8 [3],[23],[33]                
Investment, Identifier [Axis]: Excelitas Technologies Corp, Technology Hardware & Equipment 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.9                    
Fair Value, ending balance 1.9 [4],[42]   1.9 [3],[17]                
Investment, Identifier [Axis]: Excelitas Technologies Corp, Technology Hardware & Equipment 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.4                    
Fair Value, ending balance 2.4 [4],[24]   2.4 [3],[23]                
Investment, Identifier [Axis]: Excelitas Technologies Corp, Technology Hardware & Equipment 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 23.5                    
Fair Value, ending balance 23.6 [4],[24]   23.5 [3],[23]                
Investment, Identifier [Axis]: Florida Food Products LLC, Revolver, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 20.5                    
Investment, Identifier [Axis]: Florida Food Products LLC, Revolver, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 4.0                    
Investment, Identifier [Axis]: Follett Software Co, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[27],[28] 72.9                    
Fair Value, ending balance 72.0 [4],[21],[43],[47]   72.9 [3],[19],[27],[28]                
Investment, Identifier [Axis]: Follett Software Co, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 9.9                    
Fair Value, ending balance 9.9 [4],[24]   9.9 [3],[23]                
Investment, Identifier [Axis]: Fortna Group Inc, Revolver, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 54.7                    
Investment, Identifier [Axis]: Fortna Group Inc, Revolver, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 27.4                    
Investment, Identifier [Axis]: Foundation Consumer Brands LLC, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27],[41] 65.3                    
Fair Value, ending balance 76.1 [4],[18],[42],[44],[47]   65.3 [3],[17],[27],[41]                
Investment, Identifier [Axis]: Foundation Consumer Brands LLC, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.6                    
Fair Value, ending balance 7.7 [4],[24]   6.6 [3],[23]                
Investment, Identifier [Axis]: Foundation Risk Partners Corp, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 79.0                    
Fair Value, ending balance 53.5 [4],[18],[42],[44]   79.0 [3],[17],[41]                
Investment, Identifier [Axis]: Foundation Risk Partners Corp, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 11.8                    
Fair Value, ending balance 28.6 [4],[18],[42]   11.8 [3],[23]                
Investment, Identifier [Axis]: Foundation Risk Partners Corp, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.4                    
Fair Value, ending balance 11.8 [4],[24]   6.4 [3],[23]                
Investment, Identifier [Axis]: Foundation Risk Partners Corp, Insurance 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 2.8                    
Investment, Identifier [Axis]: Foundation Risk Partners Corp, Insurance 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 15.9                    
Investment, Identifier [Axis]: Frontline Road Safety LLC, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[42],[47] 46.1                    
Investment, Identifier [Axis]: Frontline Road Safety LLC, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18] 13.0                    
Investment, Identifier [Axis]: Frontline Road Safety LLC, Transportation 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 26.4                    
Investment, Identifier [Axis]: Frontline Road Safety LLC, Transportation 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 15.7                    
Investment, Identifier [Axis]: Frontline Road Safety LLC, Transportation 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 1.3                    
Investment, Identifier [Axis]: Fronton BV, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 1.8 1.8                
Gross Additions [6]     0.0                
Gross Reductions [8]     (1.7)                
Net Realized Gain (Loss)     1.7                
Net Change in Unrealized Appreciation (Depreciation)     (1.8)                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Galaxy Universal LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 86.3 86.4 86.4                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions (0.3) [7]   (0.8) [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.7                
Fair Value, ending balance 86.0   86.3                
Investment Income 2.4 [9]   10.2 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.2 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Galaxy Universal LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 18.5 18.1 18.1                
Gross Additions 1.9 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.4)   0.4                
Fair Value, ending balance 20.0   18.5                
Investment Income 0.5 [9]   2.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.1 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Galaxy Universal LLC 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [5] 45.5                    
Gross Reductions [7] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (0.9)                    
Fair Value, ending balance 44.6   0.0                
Investment Income [9] 1.1                    
PIK Income [9] 0.0                    
Fee income [9] 2.0                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Galaxy Universal LLC 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [5] 37.5                    
Gross Reductions [7] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 37.5   0.0                
Investment Income [9] 0.1                    
PIK Income [9] 0.0                    
Fee income [9] 1.1                    
Dividend and Other Income [9] 0.0                    
Investment, Identifier [Axis]: Galaxy Universal LLC, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 49.2 0.5 0.5                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions (30.4) [7]   0.0 [8]                
Net Realized Gain (Loss) 8.5   0.0                
Net Change in Unrealized Appreciation (Depreciation) (8.5)   48.7                
Fair Value, ending balance 18.8   49.2                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Common Stock, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[26],[30],[48] 49.2                    
Fair Value, ending balance 18.8 [4],[29],[31],[50]   49.2 [3],[26],[30],[48]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Consumer Durables & Apparel 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 86.3                    
Fair Value, ending balance 86.0 [4],[18],[29]   86.3 [3],[17],[26]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Consumer Durables & Apparel 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 18.5                    
Fair Value, ending balance 20.0 [4],[18],[29]   18.5 [3],[17],[26]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Consumer Durables & Apparel 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[29] 44.6                    
Investment, Identifier [Axis]: Galaxy Universal LLC, Consumer Durables & Apparel 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[29] 37.5                    
Investment, Identifier [Axis]: Galaxy Universal LLC, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.2 5.5 5.5                
Gross Additions 0.0 [5]   0.9 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   0.8                
Fair Value, ending balance 7.1   7.2                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.1 [9]   0.5 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Preferred Stock, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[26],[48] 7.2                    
Fair Value, ending balance 7.1 [4],[29],[50]   7.2 [3],[26],[48]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Trade Claim                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1.9 1.0 1.0                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.9                
Fair Value, ending balance 1.9   1.9                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Galaxy Universal LLC, Trade Claim, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30] 1.9                    
Fair Value, ending balance 1.9 [4],[18],[29],[31]   1.9 [3],[17],[26],[30]                
Investment, Identifier [Axis]: Galway Partners Holdings LLC, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.1                    
Fair Value, ending balance 4.3 [4],[18]   1.1 [3],[17]                
Investment, Identifier [Axis]: Galway Partners Holdings LLC, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.2                    
Fair Value, ending balance 0.5 [4],[18]   0.2 [3],[17]                
Investment, Identifier [Axis]: Galway Partners Holdings LLC, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[28],[41] 77.0                    
Fair Value, ending balance 77.2 [4],[18],[21],[42],[43],[44]   77.0 [3],[17],[19],[28],[41]                
Investment, Identifier [Axis]: Galway Partners Holdings LLC, Insurance 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 11.9                    
Fair Value, ending balance 8.8 [4],[24]   11.9 [3],[23]                
Investment, Identifier [Axis]: Galway Partners Holdings LLC, Insurance 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.2                    
Fair Value, ending balance 7.9 [4],[24]   8.2 [3],[23]                
Investment, Identifier [Axis]: General Datatech LP, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28],[41] 124.0                    
Fair Value, ending balance 122.6 [4],[18],[21],[42],[43],[44],[47]   124.0 [3],[17],[19],[27],[28],[41]                
Investment, Identifier [Axis]: Gigamon Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 9.1                    
Fair Value, ending balance 2.7 [4],[18]   9.1 [3],[17]                
Investment, Identifier [Axis]: Gigamon Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20] 102.1                    
Fair Value, ending balance 102.2 [4],[18],[22]   102.1 [3],[17],[20]                
Investment, Identifier [Axis]: Gigamon Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 6.4                    
Investment, Identifier [Axis]: Global Jet Capital LLC, Preferred Stock, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[54],[57] 175.1                    
Fair Value, ending balance 194.7 [4],[18],[31],[55],[58]   175.1 [3],[17],[30],[54],[57]                
Investment, Identifier [Axis]: Global Lending Services LLC, ABF Equity, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 2.5                    
Fair Value, ending balance 2.3 [4],[18],[35]   2.5 [3],[17],[33]                
Investment, Identifier [Axis]: Global Lending Services LLC, ABF Equity, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 5.6                    
Fair Value, ending balance 4.7 [4],[18],[35]   5.6 [3],[17],[33]                
Investment, Identifier [Axis]: Global Lending Services LLC, ABF Equity, Financial Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 57.2                    
Fair Value, ending balance 50.8 [4],[18],[35]   57.2 [3],[17],[33]                
Investment, Identifier [Axis]: Global Lending Services LLC, ABF Equity, Financial Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 0.1                    
Fair Value, ending balance 0.2 [4],[18],[31],[35]   0.1 [3],[17],[30],[33]                
Investment, Identifier [Axis]: Global Lending Services LLC, Bond, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 0.3                    
Fair Value, ending balance [3],[17],[33]     0.3                
Investment, Identifier [Axis]: Global Lending Services LLC, Bond, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 0.3                    
Investment, Identifier [Axis]: Global Lending Services LLC, Bond, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 0.2                    
Investment, Identifier [Axis]: Gracent LLC                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 29.6 24.5 24.5                
Gross Additions 1.2 [11]   4.8 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.2)   0.3                
Fair Value, ending balance 30.6   29.6                
Investment Income 0.2 [15]   0.0 [16]                
PIK Income 1.0 [15]   4.8 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Gracent LLC, Class A Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Gracent LLC, Class A Common Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[32],[48] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[34],[50]   0.0 [3],[30],[32],[48]                
Investment, Identifier [Axis]: Gracent LLC, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 29.6                    
Fair Value, ending balance 30.6 [4],[18],[34]   29.6 [3],[17],[32]                
Investment, Identifier [Axis]: Gracent LLC, Preferred Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 5.0 3.8 3.8                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (1.0)   1.2                
Fair Value, ending balance 4.0   5.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Gracent LLC, Preferred Equity, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[32],[48] 5.0                    
Fair Value, ending balance 4.0 [4],[31],[34],[50]   5.0 [3],[30],[32],[48]                
Investment, Identifier [Axis]: Gracent LLC, Preferred Stock A                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     (8.0)                
Net Change in Unrealized Appreciation (Depreciation)     8.0                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Gracent LLC, Preferred Stock B                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Gracent LLC, Preferred Stock B, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[32],[48] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[34],[50]   0.0 [3],[30],[32],[48]                
Investment, Identifier [Axis]: Granicus Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 16.5                    
Fair Value, ending balance 16.5 [4],[18],[42]   16.5 [3],[17]                
Investment, Identifier [Axis]: Granicus Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 5.0                    
Fair Value, ending balance 5.0 [4],[18],[42]   5.0 [3],[17]                
Investment, Identifier [Axis]: Granicus Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.3                    
Fair Value, ending balance 2.3 [4],[24]   2.3 [3],[23]                
Investment, Identifier [Axis]: Granicus Inc, Software & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.0                    
Fair Value, ending balance 1.0 [4],[24]   1.0 [3],[23]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, ABF Equity 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 14.9 0.0 0.0                
Gross Additions 0.0 [5]   10.7 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.8)   4.2                
Fair Value, ending balance 14.1   14.9                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, ABF Equity 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 22.3 0.0 0.0                
Gross Additions 2.6 [5]   20.6 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 1.9   1.7                
Fair Value, ending balance 26.8   22.3                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, ABF Equity, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30] 14.9                    
Fair Value, ending balance 14.1 [4],[18],[29],[31]   14.9 [3],[17],[26],[30]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, ABF Equity, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30],[33] 22.3                    
Fair Value, ending balance 26.8 [4],[18],[29],[31],[35]   22.3 [3],[17],[26],[30],[33]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, Term Loan                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 33.5 0.0 0.0                
Gross Additions 1.6 [5]   33.5 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 35.1   33.5                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.7 [9]   2.4 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, Term Loan, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 33.5                    
Fair Value, ending balance 35.1 [4],[18],[29]   33.5 [3],[17],[26]                
Investment, Identifier [Axis]: GreenSky Holdings LLC, Term Loan, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[26] 3.0                    
Fair Value, ending balance 3.0 [4],[24],[29]   3.0 [3],[23],[26]                
Investment, Identifier [Axis]: H.M. Dunn Co                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 3.4 1.0 1.0                
Gross Additions [12]     2.4                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     3.4                
Investment Income [16]     0.2                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: H.M. Dunn Co., Inc.                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 34.8 35.8 35.8                
Gross Additions [12]     0.0                
Gross Reductions [14]     (1.0)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     34.8                
Investment Income [16]     4.1                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: HKA, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[33],[41] 3.5                    
Fair Value, ending balance 3.5 [4],[35],[44]   3.5 [3],[33],[41]                
Investment, Identifier [Axis]: HM Dunn Co Inc 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 34.8                    
Gross Additions [11] 0.0                    
Gross Reductions [13] (0.2)                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (1.5)                    
Fair Value, ending balance 33.1   34.8                
Investment Income [15] 0.9                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: HM Dunn Co Inc 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 3.4                    
Gross Additions [11] 1.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (0.2)                    
Fair Value, ending balance 4.2   3.4                
Investment Income [15] 0.1                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: HM Dunn Co Inc, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 34.8                    
Fair Value, ending balance 33.1 [4],[18],[34]   34.8 [3],[17],[32]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 3.4                    
Fair Value, ending balance 4.3 [4],[18],[34]   3.4 [3],[17],[32]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[32] 1.5                    
Fair Value, ending balance 0.5 [4],[24],[34]   1.5 [3],[23],[32]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Preferred Stock, Series A                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.1 25.1 25.1                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   (25.0)                
Fair Value, ending balance 0.2   0.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Preferred Stock, Series A, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[36] 0.1                    
Fair Value, ending balance 0.2 [4],[18],[31],[34],[37]   0.1 [3],[17],[30],[32],[36]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Preferred Stock, Series B                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: HM Dunn Co Inc, Preferred Stock, Series B, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[36] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[37]   0.0 [3],[17],[30],[32],[36]                
Investment, Identifier [Axis]: Hargreaves Lansdown PLC, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 180.7                    
Investment, Identifier [Axis]: Heniff Transportation Systems LLC, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[41] 93.3                    
Fair Value, ending balance 93.0 [4],[18],[21],[42],[44],[47]   93.3 [3],[17],[19],[27],[41]                
Investment, Identifier [Axis]: Heniff Transportation Systems LLC, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 11.7                    
Fair Value, ending balance 15.3 [4],[18]   11.7 [3],[17]                
Investment, Identifier [Axis]: Heniff Transportation Systems LLC, Transportation 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.1                    
Fair Value, ending balance 2.5 [4],[24]   6.1 [3],[23]                
Investment, Identifier [Axis]: Heritage Environmental Services Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 53.6                    
Fair Value, ending balance 53.5 [4],[18],[42],[47]   53.6 [3],[17],[27]                
Investment, Identifier [Axis]: Heritage Environmental Services Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 7.6                    
Fair Value, ending balance 7.6 [4],[18],[42]   7.6 [3],[17]                
Investment, Identifier [Axis]: Heritage Environmental Services Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.0                    
Fair Value, ending balance 8.0 [4],[24]   8.0 [3],[23]                
Investment, Identifier [Axis]: Heritage Environmental Services Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.0                    
Fair Value, ending balance 4.0 [4],[24]   4.0 [3],[23]                
Investment, Identifier [Axis]: Hibu Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28],[41] 89.3                    
Fair Value, ending balance 88.1 [4],[18],[21],[43],[44],[47]   89.3 [3],[17],[19],[27],[28],[41]                
Investment, Identifier [Axis]: Hibu Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 24.7                    
Fair Value, ending balance 24.4 [4],[18],[47]   24.7 [3],[17],[27]                
Investment, Identifier [Axis]: Hibu Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 20.4                    
Fair Value, ending balance 20.1 [4],[18]   20.4 [3],[17]                
Investment, Identifier [Axis]: Higginbotham Insurance Agency Inc, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 5.3                    
Fair Value, ending balance 7.5 [4],[18]   5.3 [3],[17]                
Investment, Identifier [Axis]: Higginbotham Insurance Agency Inc, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 12.9                    
Fair Value, ending balance 10.6 [4],[24]   12.9 [3],[23]                
Investment, Identifier [Axis]: Highgate Hotels Inc, Consumer Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 34.0                    
Fair Value, ending balance 33.9 [4],[18],[42]   34.0 [3],[17]                
Investment, Identifier [Axis]: Highgate Hotels Inc, Consumer Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.2                    
Fair Value, ending balance 1.6 [4],[18]   4.2 [3],[23]                
Investment, Identifier [Axis]: Highgate Hotels Inc, Consumer Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 2.6                    
Investment, Identifier [Axis]: Home Partners JV 2, ABF Equity 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.2 0.2                
Gross Additions [6]     0.0                
Gross Reductions [8]     (0.2)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Home Partners JV 2, ABF Equity 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 4.2 4.2                
Gross Additions [6]     0.0                
Gross Reductions [8]     (4.1)                
Net Realized Gain (Loss)     (0.3)                
Net Change in Unrealized Appreciation (Depreciation)     0.2                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Home Partners JV 2, Structured Mezzanine                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 11.4 11.4                
Gross Additions [6]     1.4                
Gross Reductions [8]     (12.8)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     1.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Homrich & Berg Inc, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.1                    
Fair Value, ending balance 0.5 [4],[18]   0.1 [3],[17]                
Investment, Identifier [Axis]: Homrich & Berg Inc, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[27] 6.3                    
Fair Value, ending balance 6.3 [4],[47]   6.3 [3],[27]                
Investment, Identifier [Axis]: Homrich & Berg Inc, Financial Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.4                    
Fair Value, ending balance 1.0 [4],[24]   1.4 [3],[23]                
Investment, Identifier [Axis]: Homrich & Berg Inc, Financial Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.5                    
Fair Value, ending balance [3],[23]     7.5                
Investment, Identifier [Axis]: Horizon CTS Buyer LLC, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[43],[59] 72.8                    
Investment, Identifier [Axis]: Horizon CTS Buyer LLC, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18] 1.4                    
Investment, Identifier [Axis]: Horizon CTS Buyer LLC, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 13.7                    
Investment, Identifier [Axis]: Horizon CTS Buyer LLC, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 15.9                    
Investment, Identifier [Axis]: IQUW UK Ltd, Bond, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 5.8                    
Investment, Identifier [Axis]: Imagine Communications Corp, Common Stock, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.7                    
Fair Value, ending balance 0.2 [4],[18],[31]   0.7 [3],[17],[30]                
Investment, Identifier [Axis]: Individual FoodService, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 74.8                    
Fair Value, ending balance 75.0 [4],[18],[42]   74.8 [3],[17]                
Investment, Identifier [Axis]: Individual FoodService, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.7                    
Fair Value, ending balance 1.7 [4],[24]   1.7 [3],[23]                
Investment, Identifier [Axis]: Industria Chimica Emiliana Srl, Pharmaceuticals, Biotechnology & Life Sciences                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 86.6                    
Fair Value, ending balance 92.1 [4],[18],[35]   86.6 [3],[17],[33]                
Investment, Identifier [Axis]: Industry City TI Lessor LP, Consumer Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[36] 16.1                    
Fair Value, ending balance 14.7 [4],[18],[37]   16.1 [3],[17],[36]                
Investment, Identifier [Axis]: Inhabit IQ, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 3.6                    
Investment, Identifier [Axis]: Inhabit IQ, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 2.2                    
Investment, Identifier [Axis]: Insight Global LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20] 63.0                    
Fair Value, ending balance 63.2 [4],[18],[22],[42]   63.0 [3],[17],[20]                
Investment, Identifier [Axis]: Insight Global LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 28.5                    
Fair Value, ending balance 36.6 [4],[24]   28.5 [3],[23]                
Investment, Identifier [Axis]: Insight Global LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.6                    
Fair Value, ending balance [3],[23]     7.6                
Investment, Identifier [Axis]: Insightsoftware.Com Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.6                    
Fair Value, ending balance 1.6 [4],[18]   1.6 [3],[17]                
Investment, Identifier [Axis]: Insightsoftware.Com Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 16.7                    
Fair Value, ending balance 16.7 [4],[18],[42]   16.7 [3],[17]                
Investment, Identifier [Axis]: Insightsoftware.Com Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 5.5                    
Fair Value, ending balance 5.5 [4],[24]   5.5 [3],[23]                
Investment, Identifier [Axis]: Insightsoftware.Com Inc, Software & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 5.3                    
Fair Value, ending balance 5.3 [4],[24]   5.3 [3],[23]                
Investment, Identifier [Axis]: Integrity Marketing Group LLC, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 98.6                    
Fair Value, ending balance 99.1 [4],[18],[42]   98.6 [3],[17]                
Investment, Identifier [Axis]: Integrity Marketing Group LLC, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.1                    
Fair Value, ending balance 0.1 [4],[24]   0.1 [3],[23]                
Investment, Identifier [Axis]: Integrity Marketing Group LLC, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.5                    
Fair Value, ending balance 1.5 [4],[24]   1.5 [3],[23]                
Investment, Identifier [Axis]: J S Held LLC, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 89.2                    
Fair Value, ending balance 83.3 [4],[18],[42],[47]   89.2 [3],[17],[27]                
Investment, Identifier [Axis]: J S Held LLC, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.9                    
Fair Value, ending balance 5.4 [4],[18]   6.9 [3],[23]                
Investment, Identifier [Axis]: J S Held LLC, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 14.8                    
Fair Value, ending balance 6.9 [4],[24]   14.8 [3],[23]                
Investment, Identifier [Axis]: J S Held LLC, Insurance 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 14.8                    
Investment, Identifier [Axis]: JW Aluminum Co                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 76.6 77.1 77.1                
Gross Additions 0.0 [11]   0.2 [12]                
Gross Reductions (76.4) [13]   0.0 [14]                
Net Realized Gain (Loss) 0.3   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.5)   (0.7)                
Fair Value, ending balance 0.0   76.6                
Investment Income 1.9 [15]   8.1 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: JW Aluminum Co, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 2.5 2.5 2.5                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 2.5   2.5                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: JW Aluminum Co, Common Stock, Materials                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[54],[57] 2.5                    
Fair Value, ending balance 2.5 [4],[18],[31],[34],[55],[58]   2.5 [3],[17],[30],[32],[54],[57]                
Investment, Identifier [Axis]: JW Aluminum Co, Materials                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[36],[46] 76.6                    
Fair Value, ending balance [3],[17],[32],[36],[46]     76.6                
Investment, Identifier [Axis]: JW Aluminum Co, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 152.3 148.7 148.7                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (21.1) [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.5)   3.6                
Fair Value, ending balance 130.7   152.3                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: JW Aluminum Co, Preferred Stock, Materials                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[38],[54],[57] 152.3                    
Fair Value, ending balance 130.7 [4],[18],[31],[34],[39],[55],[58]   152.3 [3],[17],[30],[32],[38],[54],[57]                
Investment, Identifier [Axis]: KKR Altitude II Offshore Aggregator LP, Partnership Interest                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 146.7 65.6 65.6                
Gross Additions 0.0 [11]   74.2 [12]                
Gross Reductions (37.7) [13]   0.0 [14]                
Net Realized Gain (Loss) 3.3   0.0                
Net Change in Unrealized Appreciation (Depreciation) (2.0)   6.9                
Fair Value, ending balance 110.3   146.7                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 3.5 [15]   6.6 [16]                
Investment, Identifier [Axis]: KKR Altitude II Offshore Aggregator LP, Partnership Interest, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 146.7                    
Fair Value, ending balance 110.3 [4],[18],[34],[35]   146.7 [3],[17],[32],[33]                
Investment, Identifier [Axis]: KKR Central Park Leasing Aggregator L.P., Partnership Interest                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 15.8 15.3 15.3                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.2   0.5                
Fair Value, ending balance 16.0   15.8                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: KKR Central Park Leasing Aggregator L.P., Partnership Interest, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33],[38] 15.8                    
Fair Value, ending balance 16.0 [4],[18],[31],[34],[35],[39]   15.8 [3],[17],[30],[32],[33],[38]                
Investment, Identifier [Axis]: KKR Chord IP Aggregator LP, Partnership Interest                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.1 99.9 99.9                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   (120.3) [14]                
Net Realized Gain (Loss) 0.0   30.7                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (10.2)                
Fair Value, ending balance 0.1   0.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.1 [15]   0.5 [16]                
Investment, Identifier [Axis]: KKR Chord IP Aggregator LP, Partnership Interest, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 0.1                    
Fair Value, ending balance 0.1 [4],[18],[34],[35]   0.1 [3],[17],[32],[33]                
Investment, Identifier [Axis]: KKR Rocket Loans Aggregator LLC, Partnership Interest                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 4.3 8.3 8.3                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (0.7) [13]   (4.3) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.3                
Fair Value, ending balance 3.6   4.3                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.3 [16]                
Investment, Identifier [Axis]: KKR Rocket Loans Aggregator LLC, Partnership Interest, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 4.3                    
Fair Value, ending balance 3.6 [4],[18],[31],[34],[35]   4.3 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: KKR Zeno Aggregator LP (K2 Aviation), Partnership Interest                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.2 11.8 11.8                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions (2.9) [13]   (9.0) [14]                
Net Realized Gain (Loss) 0.3   0.3                
Net Change in Unrealized Appreciation (Depreciation) (3.0)   4.1                
Fair Value, ending balance 1.6   7.2                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 4.0 [15]   2.6 [16]                
Investment, Identifier [Axis]: KKR Zeno Aggregator LP (K2 Aviation), Partnership Interest, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 7.2                    
Fair Value, ending balance 1.6 [4],[18],[34],[35]   7.2 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Karman Space Inc, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 94.2                    
Fair Value, ending balance 93.5 [4],[18]   94.2 [3],[17]                
Investment, Identifier [Axis]: Karman Space Inc, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 7.3                    
Fair Value, ending balance 7.3 [4],[24]   7.3 [3],[17]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 201.6 0.0 0.0                
Gross Additions 5.4 [11]   198.9 [12]                
Gross Reductions (0.5) [13]   (1.4) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.3)   4.1                
Fair Value, ending balance 206.2   201.6                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 5.2 [15]   17.2 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 87.7 0.0 0.0                
Gross Additions 3.0 [11]   88.2 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (6.2)   (0.5)                
Fair Value, ending balance 84.5   87.7                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 2.9 [15]   9.3 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[36],[41] 201.6                    
Fair Value, ending balance 206.2 [4],[18],[34],[37],[44]   201.6 [3],[17],[32],[36],[41]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[36],[41] 87.7                    
Fair Value, ending balance 84.5 [4],[18],[34],[37],[44]   87.7 [3],[17],[32],[36],[41]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[32] 5.5                    
Fair Value, ending balance [3],[23],[32]     5.5                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Common Stock, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[36],[41] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[37],[44]   0.0 [3],[17],[30],[32],[36],[41]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 15.1 0.0 0.0                
Gross Additions 0.0 [11]   48.3 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 4.1   (33.2)                
Fair Value, ending balance 19.2   15.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kellermeyer Bergensons Services LLC, Preferred Stock, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[36],[41] 15.1                    
Fair Value, ending balance 19.2 [4],[18],[31],[34],[37],[44]   15.1 [3],[17],[30],[32],[36],[41]                
Investment, Identifier [Axis]: Kestra Financial Inc, Preferred Equity, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18] 1.8                    
Investment, Identifier [Axis]: Kestra Financial Inc, Preferred Equity, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 9.2                    
Investment, Identifier [Axis]: Kilter Finance, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.5 0.5 0.5                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.5   0.5                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kilter Finance, ABF Equity, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 0.5                    
Fair Value, ending balance 0.5 [4],[18],[31],[34],[35]   0.5 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Kilter Finance, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 85.4 99.7 99.7                
Gross Additions 0.0 [11]   1.5 [12]                
Gross Reductions (15.7) [13]   (15.8) [14]                
Net Realized Gain (Loss) 0.0   0.8                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (0.8)                
Fair Value, ending balance 69.7   85.4                
Investment Income 2.3 [15]   12.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Kilter Finance, Preferred Stock, Insurance                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 85.4                    
Fair Value, ending balance 69.7 [4],[18],[34],[35]   85.4 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Laboratoires Vivacy SAS, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 0.1                    
Fair Value, ending balance 0.1 [4],[18],[35]   0.1 [3],[17],[33]                
Investment, Identifier [Axis]: Laboratoires Vivacy SAS, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 0.5                    
Fair Value, ending balance 0.5 [4],[24],[35]   0.5 [3],[23],[33]                
Investment, Identifier [Axis]: Lakeview Farms Inc, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19] 67.1                    
Fair Value, ending balance [3],[17],[19]     67.1                
Investment, Identifier [Axis]: Lakeview Farms Inc, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 2.8                    
Fair Value, ending balance [3],[17]     2.8                
Investment, Identifier [Axis]: Lakeview Farms Inc, Food, Beverage & Tobacco 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.0                    
Fair Value, ending balance [3],[23]     4.0                
Investment, Identifier [Axis]: Lazer Logistics Inc, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 24.3                    
Fair Value, ending balance 0.5 [4],[18]   24.3 [3],[17],[27]                
Investment, Identifier [Axis]: Lazer Logistics Inc, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.9                    
Fair Value, ending balance 24.3 [4],[18],[42],[47]   1.9 [3],[23]                
Investment, Identifier [Axis]: Lazer Logistics Inc, Transportation 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 5.7                    
Fair Value, ending balance 1.4 [4],[24]   5.7 [3],[23]                
Investment, Identifier [Axis]: Lazer Logistics Inc, Transportation 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 5.7                    
Investment, Identifier [Axis]: Legends Hospitality LLC, Consumer Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.4                    
Fair Value, ending balance 6.4 [4],[18]   1.4 [3],[17]                
Investment, Identifier [Axis]: Legends Hospitality LLC, Consumer Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[27],[28] 117.7                    
Fair Value, ending balance 118.9 [4],[21],[43],[47]   117.7 [3],[19],[27],[28]                
Investment, Identifier [Axis]: Legends Hospitality LLC, Consumer Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 12.4                    
Fair Value, ending balance 7.4 [4],[24]   12.4 [3],[23]                
Investment, Identifier [Axis]: Legends Hospitality LLC, Consumer Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.9                    
Fair Value, ending balance 6.9 [4],[24]   6.9 [3],[23]                
Investment, Identifier [Axis]: Leia Acquisition Ltd. (fka Swift Worldwide Resources Holdco Ltd), Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.1                    
Fair Value, ending balance 0.1 [4],[18]   0.1 [3],[17]                
Investment, Identifier [Axis]: Lennar Corp, ABF Equity, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 16.4                    
Fair Value, ending balance 18.5 [4],[18],[35]   16.4 [3],[17],[33]                
Investment, Identifier [Axis]: Lennar Corp, Term Loan, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 14.9                    
Investment, Identifier [Axis]: Lennar Corp, Term Loan, Consumer Durables & Apparel 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 13.7                    
Fair Value, ending balance [3],[17],[33]     13.7                
Investment, Identifier [Axis]: Lennar Corp, Term Loan, Consumer Durables & Apparel 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 1.0                    
Fair Value, ending balance [3],[23],[33]     1.0                
Investment, Identifier [Axis]: Lexitas Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.3                    
Fair Value, ending balance 2.8 [4],[18]   1.3 [3],[17]                
Investment, Identifier [Axis]: Lexitas Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[20],[41] 118.3                    
Fair Value, ending balance 118.0 [4],[18],[21],[22],[42],[44]   118.3 [3],[17],[19],[20],[41]                
Investment, Identifier [Axis]: Lexitas Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.1                    
Fair Value, ending balance 5.6 [4],[24]   7.1 [3],[23]                
Investment, Identifier [Axis]: Lexitas Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 28.9                    
Fair Value, ending balance 28.9 [4],[24]   28.9 [3],[23]                
Investment, Identifier [Axis]: Lionbridge Technologies Inc, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[20],[27],[28],[36] 96.3                    
Fair Value, ending balance 93.0 [4],[18],[21],[22],[37],[43],[47]   96.3 [3],[17],[19],[20],[27],[28],[36]                
Investment, Identifier [Axis]: Lipari Foods LLC, Common Stock, Consumer Staples Distribution & Retail                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 4.2                    
Fair Value, ending balance 3.3 [4],[18],[31]   4.2 [3],[17],[30]                
Investment, Identifier [Axis]: Lipari Foods LLC, Consumer Staples Distribution & Retail                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20],[27],[41] 98.2                    
Fair Value, ending balance 97.2 [4],[18],[22],[44],[47]   98.2 [3],[17],[20],[27],[41]                
Investment, Identifier [Axis]: Lloyd's Register Quality Assurance Ltd, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 17.2                    
Fair Value, ending balance 19.5 [4],[18],[35]   17.2 [3],[17],[33]                
Investment, Identifier [Axis]: Lloyd's Register Quality Assurance Ltd, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.1                    
Fair Value, ending balance 4.4 [4],[18],[35]   2.1 [3],[23],[33]                
Investment, Identifier [Axis]: Lloyd's Register Quality Assurance Ltd, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 12.7                    
Fair Value, ending balance 8.4 [4],[24],[35]   12.7 [3],[23],[33]                
Investment, Identifier [Axis]: MAI Capital Management LLC, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 2.1                    
Fair Value, ending balance 2.7 [4],[18]   2.1 [3],[17]                
Investment, Identifier [Axis]: MAI Capital Management LLC, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.3                    
Fair Value, ending balance 0.6 [4],[18]   0.3 [3],[17]                
Investment, Identifier [Axis]: MAI Capital Management LLC, Financial Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 4.6                    
Fair Value, ending balance 4.1 [4],[24]   4.6 [3],[23]                
Investment, Identifier [Axis]: MAI Capital Management LLC, Financial Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.2                    
Fair Value, ending balance 1.9 [4],[24]   2.2 [3],[23]                
Investment, Identifier [Axis]: MB2 Dental Solutions LLC, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[28] 140.9                    
Fair Value, ending balance 147.2 [4],[18],[21],[42],[43]   140.9 [3],[17],[19],[28]                
Investment, Identifier [Axis]: MB2 Dental Solutions LLC, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 38.8                    
Fair Value, ending balance 33.1 [4],[24]   38.8 [3],[23]                
Investment, Identifier [Axis]: MB2 Dental Solutions LLC, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 10.7                    
Fair Value, ending balance 10.7 [4],[24]   10.7 [3],[23]                
Investment, Identifier [Axis]: Magna Legal Services LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 4.5                    
Fair Value, ending balance 23.3 [4],[18],[42],[44]   4.5 [3],[17]                
Investment, Identifier [Axis]: Magna Legal Services LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 23.5                    
Fair Value, ending balance 9.8 [4],[18]   23.5 [3],[17],[41]                
Investment, Identifier [Axis]: Magna Legal Services LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.2                    
Fair Value, ending balance 2.2 [4],[24]   2.2 [3],[23]                
Investment, Identifier [Axis]: Magna Legal Services LLC, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.9                    
Fair Value, ending balance 3.6 [4],[24]   8.9 [3],[23]                
Investment, Identifier [Axis]: Magna Legal Services LLC, Common Stock, Commercial & Professional Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[52] 7.1                    
Fair Value, ending balance 6.9 [4],[31],[53]   7.1 [3],[30],[52]                
Investment, Identifier [Axis]: Maverick Natural Resources LLC, Common Stock, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[48],[60] 37.4                    
Fair Value, ending balance [3],[48],[60]     37.4                
Investment, Identifier [Axis]: Med-Metrix, Common Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[52] 4.2                    
Fair Value, ending balance 5.0 [4],[53]   4.2 [3],[52]                
Investment, Identifier [Axis]: Med-Metrix, Preferred Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[52] 1.5                    
Fair Value, ending balance 3.8 [4],[53]   1.5 [3],[52]                
Investment, Identifier [Axis]: Med-Metrix, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20],[28],[41] 120.3                    
Fair Value, ending balance 119.0 [4],[18],[22],[43],[44]   120.3 [3],[17],[20],[28],[41]                
Investment, Identifier [Axis]: Med-Metrix, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.8                    
Fair Value, ending balance 7.8 [4],[24]   7.8 [3],[23]                
Investment, Identifier [Axis]: Medallia Inc, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 220.9                    
Fair Value, ending balance 216.9 [4],[18],[44]   220.9 [3],[17],[41]                
Investment, Identifier [Axis]: Mercer Advisors Inc, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 17.1                    
Fair Value, ending balance 23.4 [4],[18],[47]   17.1 [3],[17],[27]                
Investment, Identifier [Axis]: Mercer Advisors Inc, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 25.9                    
Fair Value, ending balance 19.9 [4],[24]   25.9 [3],[23]                
Investment, Identifier [Axis]: Miami Beach Medical Group LLC, Common Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[31] 7.0                    
Investment, Identifier [Axis]: Miami Beach Medical Group LLC, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[38] 11.5                    
Fair Value, ending balance [3],[17],[30],[38]     11.5                
Investment, Identifier [Axis]: Misys Ltd, Preferred Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 86.8                    
Fair Value, ending balance 90.9 [4],[18],[35]   86.8 [3],[17],[33]                
Investment, Identifier [Axis]: Misys Ltd, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 1.0                    
Fair Value, ending balance 0.4 [4],[18],[35]   1.0 [3],[17],[33]                
Investment, Identifier [Axis]: Misys Ltd, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 0.6                    
Fair Value, ending balance 1.1 [4],[24],[35]   0.6 [3],[23],[33]                
Investment, Identifier [Axis]: Model N Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 29.8                    
Fair Value, ending balance 29.8 [4],[18],[42]   29.8 [3],[17]                
Investment, Identifier [Axis]: Model N Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.1                    
Fair Value, ending balance 6.1 [4],[24]   6.1 [3],[23]                
Investment, Identifier [Axis]: Model N Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.2                    
Fair Value, ending balance 3.2 [4],[24]   3.2 [3],[23]                
Investment, Identifier [Axis]: My Community Homes PropCo 2, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 15.6                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (4.9)                    
Fair Value, ending balance 10.7   15.6                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: My Community Homes PropCo 2, ABF Equity 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 78.8 78.8                
Gross Additions [12]     0.0                
Gross Reductions [14]     (81.1)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     2.3                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: My Community Homes PropCo 2, ABF Equity 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 15.6 0.0 0.0                
Gross Additions [12]     20.3                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (4.7)                
Fair Value, ending balance     15.6                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: My Community Homes PropCo 2, ABF Equity, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 15.6                    
Fair Value, ending balance 10.7 [4],[18],[31],[34],[35]   15.6 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: My Community Homes PropCo 2, Term Loan                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 64.4 0.0 0.0                
Gross Additions 1.2 [11]   64.4 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 65.6   64.4                
Investment Income 0.0 [15]   0.1 [16]                
PIK Income 1.2 [15]   3.7 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: My Community Homes PropCo 2, Term Loan, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 64.4                    
Fair Value, ending balance 65.6 [4],[18],[34],[35]   64.4 [3],[17],[32],[33]                
Investment, Identifier [Axis]: NBG Home, Consumer Durables & Apparel 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 10.1                    
Fair Value, ending balance 10.1 [4],[18],[31]   10.1 [3],[17],[30]                
Investment, Identifier [Axis]: NBG Home, Consumer Durables & Apparel 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[38] 5.4                    
Fair Value, ending balance 4.1 [4],[18],[31],[39]   5.4 [3],[17],[30],[38]                
Investment, Identifier [Axis]: NCI Inc                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 32.1 32.2 32.2                
Gross Additions 0.0 [11]   1.0 [12]                
Gross Reductions (0.3) [13]   (1.1) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 31.8   32.1                
Investment Income 0.9 [15]   2.1 [16]                
PIK Income 0.0 [15]   2.1 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: NCI Inc, Class A-1 Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: NCI Inc, Class A-1 Common Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34]   0.0 [3],[17],[30],[32]                
Investment, Identifier [Axis]: NCI Inc, Class B-1 Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: NCI Inc, Class B-1 Common Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34]   0.0 [3],[17],[30],[32]                
Investment, Identifier [Axis]: NCI Inc, Class C Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 33.1 19.7 19.7                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 3.3   13.4                
Fair Value, ending balance 36.4   33.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: NCI Inc, Class C Common Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 33.1                    
Fair Value, ending balance 36.4 [4],[18],[31],[34]   33.1 [3],[17],[30],[32]                
Investment, Identifier [Axis]: NCI Inc, Class I-1 Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: NCI Inc, Class I-1 Common Stock, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34]   0.0 [3],[17],[30],[32]                
Investment, Identifier [Axis]: NCI Inc, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 32.1                    
Fair Value, ending balance 31.8 [4],[18],[34]   32.1 [3],[17],[32]                
Investment, Identifier [Axis]: Net Documents, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.8                    
Fair Value, ending balance 1.7 [4],[18]   1.8 [3],[17]                
Investment, Identifier [Axis]: Net Documents, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 33.3                    
Fair Value, ending balance 33.2 [4],[18],[42]   33.3 [3],[17]                
Investment, Identifier [Axis]: Net Documents, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.6                    
Fair Value, ending balance 2.8 [4],[24]   2.6 [3],[23]                
Investment, Identifier [Axis]: Netsmart Technologies Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 46.8                    
Fair Value, ending balance 47.6 [4],[18],[42]   46.8 [3],[17]                
Investment, Identifier [Axis]: Netsmart Technologies Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.2                    
Fair Value, ending balance 6.3 [4],[24]   6.2 [3],[23]                
Investment, Identifier [Axis]: Netsmart Technologies Inc, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.3                    
Fair Value, ending balance 6.3 [4],[24]   6.3 [3],[23]                
Investment, Identifier [Axis]: New Era Technology Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[20] 24.4                    
Fair Value, ending balance 19.2 [4],[21],[22],[31],[39]   24.4 [3],[19],[20]                
Investment, Identifier [Axis]: New Era Technology Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 4.6                    
Fair Value, ending balance 3.6 [4],[18],[31],[39]   4.6 [3],[17]                
Investment, Identifier [Axis]: NewStar Clarendon 2014-1A Class D, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 1.9                    
Fair Value, ending balance 1.4 [4],[18],[35]   1.9 [3],[17],[33]                
Investment, Identifier [Axis]: Nordic Climate Group Holding AB, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 43.5                    
Fair Value, ending balance 15.6 [4],[18],[35]   43.5 [3],[17],[33]                
Investment, Identifier [Axis]: Nordic Climate Group Holding AB, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 31.2                    
Fair Value, ending balance 17.3 [4],[18],[35]   31.2 [3],[17],[33]                
Investment, Identifier [Axis]: Nordic Climate Group Holding AB, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 4.8                    
Fair Value, ending balance 16.5 [4],[18],[35]   4.8 [3],[23],[33]                
Investment, Identifier [Axis]: Nordic Climate Group Holding AB, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 5.2                    
Investment, Identifier [Axis]: Norway_France, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 11.1                    
Fair Value, ending balance 10.3 [4],[18],[35]   11.1 [3],[17],[33]                
Investment, Identifier [Axis]: NovaTaste Austria GmbH, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 3.7                    
Fair Value, ending balance 4.0 [4],[18],[35]   3.7 [3],[17],[33]                
Investment, Identifier [Axis]: NovaTaste Austria GmbH, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 1.1                    
Fair Value, ending balance 1.1 [4],[24],[35]   1.1 [3],[23],[33]                
Investment, Identifier [Axis]: OEConnection LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 8.9                    
Fair Value, ending balance 19.1 [4],[18],[42]   8.9 [3],[17]                
Investment, Identifier [Axis]: OEConnection LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 10.2                    
Fair Value, ending balance 6.4 [4],[24]   10.2 [3],[23]                
Investment, Identifier [Axis]: OEConnection LLC, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.3                    
Fair Value, ending balance 6.2 [4],[24]   6.3 [3],[23]                
Investment, Identifier [Axis]: OEConnection LLC, Software & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.2                    
Fair Value, ending balance [3],[23]     6.2                
Investment, Identifier [Axis]: One Call Care Management Inc 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 4.7 4.2 4.2                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.5                
Fair Value, ending balance 4.7   4.7                
Investment Income 0.2 [9]   0.6 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: One Call Care Management Inc 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 25.1 20.6 20.6                
Gross Additions 0.1 [5]   2.7 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   1.8                
Fair Value, ending balance 25.3   25.1                
Investment Income 0.1 [9]   0.0 [10]                
PIK Income 0.6 [9]   2.4 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: One Call Care Management Inc, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1.9 1.9 1.9                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 1.9   1.9                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: One Call Care Management Inc, Common Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30] 1.9                    
Fair Value, ending balance 1.9 [4],[18],[29],[31]   1.9 [3],[17],[26],[30]                
Investment, Identifier [Axis]: One Call Care Management Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[46] 4.7                    
Fair Value, ending balance 4.7 [4],[18],[29],[45]   4.7 [3],[17],[26],[46]                
Investment, Identifier [Axis]: One Call Care Management Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[46] 25.1                    
Fair Value, ending balance 25.3 [4],[18],[29]   25.1 [3],[17],[46]                
Investment, Identifier [Axis]: One Call Care Management Inc, Preferred Stock A                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 20.7 18.5 18.5                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.4)   2.2                
Fair Value, ending balance 20.3   20.7                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: One Call Care Management Inc, Preferred Stock A, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30] 20.7                    
Fair Value, ending balance 20.3 [4],[18],[29],[31]   20.7 [3],[17],[26],[30]                
Investment, Identifier [Axis]: One Call Care Management Inc, Preferred Stock B                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 12.2 7.7 7.7                
Gross Additions 0.1 [5]   2.4 [6]                
Gross Reductions 0.0 [7]   0.0 [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   2.1                
Fair Value, ending balance 12.4   12.2                
Investment Income 0.1 [9]   0.0 [10]                
PIK Income 0.2 [9]   0.6 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: One Call Care Management Inc, Preferred Stock B, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 12.2                    
Fair Value, ending balance 12.4 [4],[18],[29]   12.2 [3],[17],[26]                
Investment, Identifier [Axis]: Opendoor Labs Inc, Structured Mezzanine, Real Estate Management & Development 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 26.4                    
Investment, Identifier [Axis]: Opendoor Labs Inc, Structured Mezzanine, Real Estate Management & Development 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 13.2                    
Investment, Identifier [Axis]: Optio Invest, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 5.7                    
Fair Value, ending balance 5.6 [4],[18],[35]   5.7 [3],[17],[33]                
Investment, Identifier [Axis]: Oxford Global Resources LLC, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28],[41] 92.9                    
Fair Value, ending balance 92.7 [4],[18],[21],[42],[43],[44],[47]   92.9 [3],[17],[19],[27],[28],[41]                
Investment, Identifier [Axis]: Oxford Global Resources LLC, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 8.6                    
Fair Value, ending balance 8.5 [4],[18],[42]   8.6 [3],[17]                
Investment, Identifier [Axis]: Oxford Global Resources LLC, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.6                    
Fair Value, ending balance 7.6 [4],[24]   7.6 [3],[23]                
Investment, Identifier [Axis]: PCI Pharma Services, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 58.7                    
Investment, Identifier [Axis]: PCI Pharma Services, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 52.0                    
Investment, Identifier [Axis]: PCI Pharma Services, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 9.9                    
Investment, Identifier [Axis]: PRG III LLC, Preferred Stock, Series A PIK                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 67.2                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (44.9)                    
Fair Value, ending balance 22.3   67.2                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: PRG III LLC, Preferred Stock, Series A PIK, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 67.2                    
Fair Value, ending balance 22.3 [4],[18],[31],[34]   67.2 [3],[17],[30],[32]                
Investment, Identifier [Axis]: PRG III LLC, Preferred Stock, Series B PIK                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.0                    
Fair Value, ending balance 0.0   0.0                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: PRG III LLC, Preferred Stock, Series B PIK, Media & Entertainment                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34]   0.0 [3],[17],[30],[32]                
Investment, Identifier [Axis]: PSC Group, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.7                    
Fair Value, ending balance 1.8 [4],[18]   1.7 [3],[17]                
Investment, Identifier [Axis]: PSC Group, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 16.0                    
Fair Value, ending balance 17.3 [4],[18],[42]   16.0 [3],[17]                
Investment, Identifier [Axis]: PSC Group, Transportation 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.7                    
Fair Value, ending balance 0.6 [4],[24]   0.7 [3],[23]                
Investment, Identifier [Axis]: PSC Group, Transportation 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.3                    
Fair Value, ending balance 2.0 [4],[24]   3.3 [3],[23]                
Investment, Identifier [Axis]: PSKW LLC (dba ConnectiveRx), Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[28] 102.3                    
Fair Value, ending balance 102.1 [4],[18],[21],[42],[43]   102.3 [3],[17],[19],[28]                
Investment, Identifier [Axis]: PartsSource Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 2.9                    
Fair Value, ending balance 4.0 [4],[18]   2.9 [3],[17]                
Investment, Identifier [Axis]: PartsSource Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 72.0                    
Fair Value, ending balance 71.8 [4],[18],[42]   72.0 [3],[17]                
Investment, Identifier [Axis]: PartsSource Inc, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.4                    
Fair Value, ending balance 0.3 [4],[24]   1.4 [3],[23]                
Investment, Identifier [Axis]: PartsSource Inc, Health Care Equipment & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 16.9                    
Fair Value, ending balance 16.9 [4],[24]   16.9 [3],[23]                
Investment, Identifier [Axis]: PayPal Europe Sarl et Cie SCA, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 78.1                    
Fair Value, ending balance 74.8 [4],[18],[35]   78.1 [3],[17],[33]                
Investment, Identifier [Axis]: Peraton Corp, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[36] 168.5                    
Fair Value, ending balance 162.7 [4],[18],[37]   168.5 [3],[17],[36]                
Investment, Identifier [Axis]: Peraton Corp, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 124.1                    
Fair Value, ending balance 119.9 [4],[18]   124.1 [3],[17]                
Investment, Identifier [Axis]: Performance Health Holdings Inc, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[20],[27],[41] 93.2                    
Fair Value, ending balance [3],[17],[20],[27],[41]     93.2                
Investment, Identifier [Axis]: Polyconcept North America Inc, Class A - 1 Units, Household & Personal Products                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 4.3                    
Fair Value, ending balance 3.6 [4],[18],[31]   4.3 [3],[17]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Revolver, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 12.6                    
Fair Value, ending balance 4.7 [4],[18]   12.6 [3],[17]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Revolver, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 17.4                    
Fair Value, ending balance 25.9 [4],[24]   17.4 [3],[23]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Warrants, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[61] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[62]   0.0 [3],[30],[61]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Warrants, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[61] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[62]   0.0 [3],[30],[61]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Warrants, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[61] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[62]   0.0 [3],[30],[61]                
Investment, Identifier [Axis]: Powin Energy Corp/NV, Warrants, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[30],[61] 0.0                    
Fair Value, ending balance 0.0 [4],[31],[62]   0.0 [3],[30],[61]                
Investment, Identifier [Axis]: Prime ST LLC, ABF Equity, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[34],[35]   0.0 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Prime ST LLC, Structured Mezzanine, Equity Real Estate Investment Trusts (REITs)                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 27.6                    
Fair Value, ending balance 27.9 [4],[18],[34],[35]   27.6 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Prime St LLC, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions 0.0 [11]   1.6 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (1.6)                
Fair Value, ending balance 0.0   0.0                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Prime St LLC, Structured Mezzanine                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 27.6 33.1 33.1                
Gross Additions 0.0 [11]   3.8 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.3   (9.3)                
Fair Value, ending balance 27.9   27.6                
Investment Income 1.1 [15]   3.2 [16]                
PIK Income 0.9 [15]   3.5 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Production Resource Group LLC 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 67.7 63.6 63.6                
Gross Additions [12]     6.8                
Gross Reductions [14]     (1.6)                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (1.1)                
Fair Value, ending balance     67.7                
Investment Income [16]     5.0                
PIK Income [16]     4.3                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Production Resource Group LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 195.9 168.6 168.6                
Gross Additions 6.9 [11]   30.0 [12]                
Gross Reductions 0.0 [13]   (0.7) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   (2.0)                
Fair Value, ending balance 202.9   195.9                
Investment Income 1.4 [15]   13.4 [16]                
PIK Income 6.9 [15]   20.9 [16]                
Fee income 0.0 [15]   5.3 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Production Resource Group LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.3 0.1 0.1                
Gross Additions 0.1 [11]   0.1 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   0.1                
Fair Value, ending balance 0.3   0.3                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Production Resource Group LLC 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 67.7                    
Gross Additions [11] 1.6                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.1                    
Fair Value, ending balance 69.4   67.7                
Investment Income [15] 0.5                    
PIK Income [15] 1.6                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Production Resource Group LLC 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 37.2 34.8 34.8                
Gross Additions 0.9 [11]   3.0 [12]                
Gross Reductions 0.0 [13]   (0.8) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.1)   0.2                
Fair Value, ending balance 38.0   37.2                
Investment Income 0.2 [15]   3.0 [16]                
PIK Income 0.9 [15]   2.4 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Production Resource Group LLC 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 107.4 0.0 0.0                
Gross Additions 2.5 [11]   105.3 [12]                
Gross Reductions 0.0 [13]   (1.0) [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.1   3.1                
Fair Value, ending balance 110.0   107.4                
Investment Income 0.6 [15]   3.0 [16]                
PIK Income 2.5 [15]   5.6 [16]                
Fee income 0.0 [15]   4.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Production Resource Group LLC 6                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0                    
Gross Additions [11] 9.6                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.7                    
Fair Value, ending balance 10.3   0.0                
Investment Income [15] 0.1                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Production Resource Group LLC, Media & Entertainment 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 208.5                    
Fair Value, ending balance 217.4 [4],[18],[34]   208.5 [3],[17],[32]                
Investment, Identifier [Axis]: Production Resource Group LLC, Media & Entertainment 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 195.9                    
Fair Value, ending balance 202.9 [4],[18],[34]   195.9 [3],[17],[32]                
Investment, Identifier [Axis]: Production Resource Group LLC, Media & Entertainment 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 0.3                    
Fair Value, ending balance 0.3 [4],[18],[34]   0.3 [3],[17],[32]                
Investment, Identifier [Axis]: Production Resource Group LLC, Media & Entertainment 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 3.8                    
Fair Value, ending balance 10.3 [4],[18],[34]   3.8 [3],[17],[32]                
Investment, Identifier [Axis]: Production Resource Group LLC, Preferred Stock, Series A PIK                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 67.2 120.7 120.7                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (53.5)                
Fair Value, ending balance     67.2                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Production Resource Group LLC, Preferred Stock, Series B PIK                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     0.0                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Proserv Acquisition LLC, Class A Common Units                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 3.5 3.5                
Gross Additions [6]     0.0                
Gross Reductions [8]     (7.3)                
Net Realized Gain (Loss)     (26.2)                
Net Change in Unrealized Appreciation (Depreciation)     30.0                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: Proserv Acquisition LLC, Class A Preferred Units                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 2.2 9.5 9.5                
Gross Additions 0.0 [5]   0.0 [6]                
Gross Reductions 0.0 [7]   (2.3) [8]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   (5.0)                
Fair Value, ending balance 2.2   2.2                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 0.0 [9]   0.0 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: Proserv Acquisition LLC, Class A Preferred Units, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26],[30],[33] 2.2                    
Fair Value, ending balance 2.2 [4],[18],[29],[31],[35]   2.2 [3],[17],[26],[30],[33]                
Investment, Identifier [Axis]: Quoizel, LLC 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.1 6.5 6.5                
Gross Additions 0.0 [11]   0.6 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 7.1   7.1                
Investment Income 0.2 [15]   0.2 [16]                
PIK Income 0.0 [15]   0.6 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quoizel, LLC 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 7.4 6.8 6.8                
Gross Additions 0.0 [11]   0.6 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 7.4   7.4                
Investment Income 0.2 [15]   0.3 [16]                
PIK Income 0.0 [15]   0.6 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quoizel, LLC, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 6.1 10.2 10.2                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.2   (4.1)                
Fair Value, ending balance 6.3   6.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quoizel, LLC, Common Stock, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 6.1                    
Fair Value, ending balance 6.3 [4],[18],[31],[34]   6.1 [3],[17],[30],[32]                
Investment, Identifier [Axis]: Quoizel, LLC, Consumer Durables & Apparel 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 7.1                    
Fair Value, ending balance 7.1 [4],[18],[34]   7.1 [3],[17],[32]                
Investment, Identifier [Axis]: Quoizel, LLC, Consumer Durables & Apparel 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 7.4                    
Fair Value, ending balance 7.4 [4],[18],[34]   7.4 [3],[17],[32]                
Investment, Identifier [Axis]: Quorum Health Corp, Private Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 10.1 7.7 7.7                
Gross Additions 0.9 [11]   3.7 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.3)   (1.3)                
Fair Value, ending balance 10.7   10.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quorum Health Corp, Private Equity, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 10.1                    
Fair Value, ending balance 10.7 [4],[18],[31],[34]   10.1 [3],[17],[30],[32]                
Investment, Identifier [Axis]: Quorum Health Corp, Trade Claim                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.9 0.9 0.9                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.9   0.9                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quorum Health Corp, Trade Claim, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.9                    
Fair Value, ending balance 0.9 [4],[18],[31],[34]   0.9 [3],[17],[30],[32]                
Investment, Identifier [Axis]: Quorum Health Corp, Trust Initial Funding Units                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.1 0.1 0.1                
Gross Additions 0.0 [11]   0.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 0.1   0.1                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Quorum Health Corp, Trust Initial Funding Units, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.1                    
Fair Value, ending balance 0.1 [4],[18],[31],[34]   0.1 [3],[17],[30],[32]                
Investment, Identifier [Axis]: RSC Insurance Brokerage Inc, Insurance 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[20] 189.5                    
Fair Value, ending balance 193.4 [4],[18],[21],[22],[42]   189.5 [3],[17],[19],[20]                
Investment, Identifier [Axis]: RSC Insurance Brokerage Inc, Insurance 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 15.0                    
Fair Value, ending balance 10.8 [4],[24]   15.0 [3],[23]                
Investment, Identifier [Axis]: RSC Insurance Brokerage Inc, Insurance 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 9.7                    
Fair Value, ending balance 9.7 [4],[24]   9.7 [3],[23]                
Investment, Identifier [Axis]: Radwell International LLC, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.4                    
Fair Value, ending balance 1.8 [4],[18]   1.4 [3],[17]                
Investment, Identifier [Axis]: Radwell International LLC, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[20],[41] 66.7                    
Fair Value, ending balance 66.8 [4],[21],[22],[44]   66.7 [3],[19],[20],[41]                
Investment, Identifier [Axis]: Radwell International LLC, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 5.5                    
Fair Value, ending balance 5.1 [4],[24]   5.5 [3],[23]                
Investment, Identifier [Axis]: Radwell International LLC, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 61.6                    
Fair Value, ending balance 61.9 [4],[24]   61.6 [3],[23]                
Investment, Identifier [Axis]: Recordati Industria Chimica e Farmaceutica SpA, Pharmaceuticals, Biotechnology & Life Sciences 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35],[45],[59] 1.1                    
Investment, Identifier [Axis]: Recordati Industria Chimica e Farmaceutica SpA, Pharmaceuticals, Biotechnology & Life Sciences 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35],[45],[59] 1.1                    
Investment, Identifier [Axis]: Reliant Rehab Hospital Cincinnati LLC, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[36] 43.7                    
Fair Value, ending balance 43.7 [4],[18],[37]   43.7 [3],[17],[36]                
Investment, Identifier [Axis]: Reliant Rehab Hospital Cincinnati LLC, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[36],[38] 15.8                    
Fair Value, ending balance 22.7 [4],[18],[31],[37],[39]   15.8 [3],[17],[30],[36],[38]                
Investment, Identifier [Axis]: Reliant Rehab Hospital Cincinnati LLC, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.0                    
Fair Value, ending balance [3],[23]     2.0                
Investment, Identifier [Axis]: Residential Opportunities I LLC, ABF Equity, Real Estate Management & Development                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.1                    
Fair Value, ending balance 0.1 [4],[18]   0.1 [3],[17]                
Investment, Identifier [Axis]: Revere Superior Holdings Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 42.1                    
Fair Value, ending balance 42.2 [4],[18],[42],[44]   42.1 [3],[17],[41]                
Investment, Identifier [Axis]: Revere Superior Holdings Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.8                    
Fair Value, ending balance 3.8 [4],[24]   3.8 [3],[23]                
Investment, Identifier [Axis]: Rialto Capital Management LLC, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 14.2                    
Fair Value, ending balance 13.9 [4],[18],[42]   14.2 [3],[17]                
Investment, Identifier [Axis]: Rialto Capital Management LLC, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.5                    
Fair Value, ending balance 0.5 [4],[24]   0.5 [3],[23]                
Investment, Identifier [Axis]: Rockefeller Capital Management LP, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 24.0                    
Fair Value, ending balance 24.9 [4],[18],[42]   24.0 [3],[17]                
Investment, Identifier [Axis]: Rockefeller Capital Management LP, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.9                    
Fair Value, ending balance 5.7 [4],[24]   6.9 [3],[23]                
Investment, Identifier [Axis]: Roemanu LLC (FKA Toorak Capital Partners LLC), ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 238.9 241.0 241.0                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (2.1)                
Fair Value, ending balance     238.9                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     4.8                
Investment, Identifier [Axis]: Roemanu LLC (FKA Toorak Capital Partners LLC), ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 238.9                    
Fair Value, ending balance [3],[17],[32]     238.9                
Investment, Identifier [Axis]: Roemanu LLC, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 238.9                    
Gross Additions [11] 0.0                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) (2.9)                    
Fair Value, ending balance 236.0   238.9                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 2.2                    
Investment, Identifier [Axis]: Roemanu LLC, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[34] 236.0                    
Investment, Identifier [Axis]: SAMBA Safety Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[41] 5.5                    
Fair Value, ending balance 5.5 [4],[44]   5.5 [3],[41]                
Investment, Identifier [Axis]: SAMBA Safety Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.5                    
Fair Value, ending balance 0.5 [4],[18]   0.5 [3],[17]                
Investment, Identifier [Axis]: SAMBA Safety Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.4                    
Fair Value, ending balance 1.4 [4],[24]   1.4 [3],[23]                
Investment, Identifier [Axis]: STV Group Inc, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.2                    
Fair Value, ending balance 1.8 [4],[18]   1.2 [3],[17]                
Investment, Identifier [Axis]: STV Group Inc, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[27] 10.0                    
Fair Value, ending balance 10.0 [4],[47]   10.0 [3],[27]                
Investment, Identifier [Axis]: STV Group Inc, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.1                    
Fair Value, ending balance 6.5 [4],[24]   7.1 [3],[23]                
Investment, Identifier [Axis]: STV Group Inc, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 11.9                    
Fair Value, ending balance 12.0 [4],[24]   11.9 [3],[23]                
Investment, Identifier [Axis]: Safe-Guard Products International LLC, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27],[28] 42.5                    
Fair Value, ending balance 42.1 [4],[42],[43],[47]   42.5 [3],[17],[27],[28]                
Investment, Identifier [Axis]: Safe-Guard Products International LLC, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 8.8                    
Fair Value, ending balance 8.8 [4],[24]   8.8 [3],[23]                
Investment, Identifier [Axis]: Saluda Grade Alternative Mortgage Trust 2022-BC2, Structured Mezzanine, Real Estate Management & Development                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 2.9                    
Fair Value, ending balance 2.9 [4],[18],[35]   2.9 [3],[17],[33]                
Investment, Identifier [Axis]: Saluda Grade Alternative Mortgage Trust 2023-LOC2, Structured Mezzanine, Real Estate Management & Development                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 7.5                    
Fair Value, ending balance 7.2 [4],[18],[35]   7.5 [3],[17],[33]                
Investment, Identifier [Axis]: Saturn Oil & Gas Inc, Common Stock, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33],[46],[54],[57] 0.5                    
Fair Value, ending balance 0.5 [4],[18],[31],[35],[45],[55],[58]   0.5 [3],[17],[30],[33],[46],[54],[57]                
Investment, Identifier [Axis]: Service Express Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 31.2                    
Fair Value, ending balance 33.0 [4],[18],[42]   31.2 [3],[17]                
Investment, Identifier [Axis]: Service Express Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.6                    
Fair Value, ending balance 5.9 [4],[24]   0.6 [3],[17]                
Investment, Identifier [Axis]: Service Express Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.4                    
Fair Value, ending balance 4.3 [4],[24]   7.4 [3],[23]                
Investment, Identifier [Axis]: Service Express Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.6                    
Fair Value, ending balance [3],[23]     3.6                
Investment, Identifier [Axis]: Shaw Development LLC, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 27.9                    
Fair Value, ending balance 26.0 [4],[18]   27.9 [3],[17]                
Investment, Identifier [Axis]: Shaw Development LLC, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 3.3                    
Fair Value, ending balance 3.1 [4],[24]   3.3 [3],[23]                
Investment, Identifier [Axis]: SitusAMC Holdings Corp, Real Estate Management & Development                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19] 16.1                    
Fair Value, ending balance 16.1 [4],[21]   16.1 [3],[19]                
Investment, Identifier [Axis]: Solera LLC, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 335.9                    
Fair Value, ending balance 335.9 [4],[18]   335.9 [3],[17]                
Investment, Identifier [Axis]: Sorenson Communications LLC, Common Stock, Telecommunication Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[54],[57] 15.1                    
Fair Value, ending balance 12.9 [4],[18],[31],[55],[58]   15.1 [3],[17],[30],[54],[57]                
Investment, Identifier [Axis]: Sorenson Communications LLC, Telecommunication Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[54] 11.9                    
Fair Value, ending balance 11.9 [4],[18],[31],[55],[58]   11.9 [3],[17],[30],[54]                
Investment, Identifier [Axis]: Sorenson Communications LLC, Telecommunication Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[54] 42.0                    
Fair Value, ending balance 42.5 [4],[18],[31],[55],[58]   42.0 [3],[17],[30],[54]                
Investment, Identifier [Axis]: Source Code LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 3.6                    
Fair Value, ending balance 3.6 [4],[42]   3.6 [3],[17]                
Investment, Identifier [Axis]: Source Code LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[28] 49.5                    
Fair Value, ending balance 49.3 [4],[21],[43]   49.5 [3],[19],[28]                
Investment, Identifier [Axis]: Spins LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[28],[36],[41] 64.2                    
Fair Value, ending balance 27.9 [4],[43]   64.2 [3],[17],[28],[36],[41]                
Investment, Identifier [Axis]: Spins LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 9.1                    
Fair Value, ending balance 4.9 [4],[24]   9.1 [3],[23]                
Investment, Identifier [Axis]: Spins LLC, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 7.9                    
Fair Value, ending balance 3.2 [4],[24]   7.9 [3],[23]                
Investment, Identifier [Axis]: Spotless Brands LLC, Consumer Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 31.0                    
Fair Value, ending balance 31.1 [4],[18],[42]   31.0 [3],[17]                
Investment, Identifier [Axis]: Spotless Brands LLC, Consumer Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 19.6                    
Fair Value, ending balance 22.6 [4],[18]   19.6 [3],[17]                
Investment, Identifier [Axis]: Spotless Brands LLC, Consumer Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 16.3                    
Fair Value, ending balance 13.5 [4],[24]   16.3 [3],[23]                
Investment, Identifier [Axis]: Star Mountain Diversified Credit Income Fund III, LP, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[33],[60] 23.4                    
Fair Value, ending balance 21.8 [4],[35],[56]   23.4 [3],[33],[60]                
Investment, Identifier [Axis]: Stuart Weitzman Inc, Common Stock, Consumer Durables & Apparel                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31]   0.0 [3],[17],[30]                
Investment, Identifier [Axis]: Summit Interconnect Inc, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28],[41] 122.4                    
Fair Value, ending balance 123.1 [4],[18],[43],[44],[47]   122.4 [3],[17],[19],[27],[28],[41]                
Investment, Identifier [Axis]: SunPower Financial, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 4.6                    
Fair Value, ending balance 2.9 [4],[18],[35]   4.6 [3],[17],[30],[33]                
Investment, Identifier [Axis]: Sweeping Corp of America Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 15.6                    
Fair Value, ending balance 15.6 [4],[18],[44]   15.6 [3],[17],[41]                
Investment, Identifier [Axis]: Sweeping Corp of America Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 30.3                    
Fair Value, ending balance 31.0 [4],[18],[44]   30.3 [3],[17],[41]                
Investment, Identifier [Axis]: Sweeping Corp of America Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 5.7                    
Fair Value, ending balance 5.7 [4],[24]   5.7 [3],[23]                
Investment, Identifier [Axis]: Sweeping Corp of America Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[41] 4.8                    
Fair Value, ending balance 4.6 [4],[18],[31],[44]   4.8 [3],[17],[30],[41]                
Investment, Identifier [Axis]: Sweeping Corp of America Inc, Commercial & Professional Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[41] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[44]   0.0 [3],[17],[30],[41]                
Investment, Identifier [Axis]: Synovus Financial Corp, ABF Equity, Banks                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 4.6                    
Fair Value, ending balance [3],[17],[33]     4.6                
Investment, Identifier [Axis]: TDC LLP, ABF Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1.9                    
Gross Additions [11] 0.0                    
Gross Reductions [13] (2.0)                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.1                    
Fair Value, ending balance 0.0   1.9                
Investment Income [15] 0.0                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: TDC LLP, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 1.9                    
Fair Value, ending balance [3],[17],[30],[32],[33]     1.9                
Investment, Identifier [Axis]: TDC LLP, Preferred Equity                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 36.8                    
Gross Additions [11] 3.6                    
Gross Reductions [13] (41.9)                    
Net Realized Gain (Loss) 1.0                    
Net Change in Unrealized Appreciation (Depreciation) 0.5                    
Fair Value, ending balance 0.0   36.8                
Investment Income [15] 0.8                    
PIK Income [15] 0.0                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: TDC LLP, Preferred Equity 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 36.8 27.8 27.8                
Gross Additions [12]     22.2                
Gross Reductions [14]     (11.5)                
Net Realized Gain (Loss)     0.3                
Net Change in Unrealized Appreciation (Depreciation)     (2.0)                
Fair Value, ending balance     36.8                
Investment Income [16]     1.8                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: TDC LLP, Preferred Equity 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 1.9 2.0 2.0                
Gross Additions [12]     0.0                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (0.1)                
Fair Value, ending balance     1.9                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: TDC LLP, Preferred Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 36.8                    
Fair Value, ending balance [3],[17],[32],[33]     36.8                
Investment, Identifier [Axis]: TIBCO Software Inc, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[46] 0.7                    
Fair Value, ending balance 0.7 [4],[18],[45]   0.7 [3],[17],[46]                
Investment, Identifier [Axis]: TalkTalk Telecom Group Ltd, Revolver, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 42.8                    
Fair Value, ending balance 42.6 [4],[18],[35]   42.8 [3],[17],[33]                
Investment, Identifier [Axis]: TalkTalk Telecom Group Ltd, Revolver, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 11.8                    
Fair Value, ending balance 14.0 [4],[24],[35]   11.8 [3],[23],[33]                
Investment, Identifier [Axis]: Tangoe LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[36],[41] 155.6                    
Fair Value, ending balance 151.8 [4],[18],[37],[44]   155.6 [3],[17],[36],[41]                
Investment, Identifier [Axis]: Tangoe LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[36],[38],[41] 0.0                    
Fair Value, ending balance 0.0 [4],[18],[31],[37],[39],[44]   0.0 [3],[17],[30],[36],[38],[41]                
Investment, Identifier [Axis]: Tekfor HoldCo (formerly Amtek Global Technology Pte Ltd), Automobiles & Components                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 4.0                    
Fair Value, ending balance 4.2 [4],[18],[31],[35]   4.0 [3],[17],[30],[33]                
Investment, Identifier [Axis]: ThermaSys Corp, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 0.0 0.0                
Gross Additions [6]     0.0                
Gross Reductions [8]     0.0                
Net Realized Gain (Loss)     (10.2)                
Net Change in Unrealized Appreciation (Depreciation)     10.2                
Fair Value, ending balance     0.0                
Investment Income [10]     0.0                
PIK Income [10]     0.0                
Fee income [10]     0.0                
Dividend and Other Income [10]     0.0                
Investment, Identifier [Axis]: ThreeSixty Group, Consumer Discretionary Distribution & Retail                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[27] 90.8                    
Fair Value, ending balance [3],[17],[27]     90.8                
Investment, Identifier [Axis]: Time Manufacturing Co, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 41.2                    
Fair Value, ending balance 40.2 [4],[18]   41.2 [3],[17]                
Investment, Identifier [Axis]: Time Manufacturing Co, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 4.4                    
Fair Value, ending balance 6.2 [4],[18]   4.4 [3],[17]                
Investment, Identifier [Axis]: Time Manufacturing Co, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 12.9                    
Fair Value, ending balance 13.1 [4],[18]   12.9 [3],[17]                
Investment, Identifier [Axis]: Time Manufacturing Co, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 17.3                    
Fair Value, ending balance 14.8 [4],[24]   17.3 [3],[23]                
Investment, Identifier [Axis]: Trescal SA, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 4.8                    
Fair Value, ending balance 6.3 [4],[18],[35]   4.8 [3],[17],[33]                
Investment, Identifier [Axis]: Trescal SA, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 4.3                    
Fair Value, ending balance 5.4 [4],[24],[35]   4.3 [3],[17],[33]                
Investment, Identifier [Axis]: Trescal SA, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 7.4                    
Fair Value, ending balance [3],[23],[33]     7.4                
Investment, Identifier [Axis]: Trinseo Materials Operating SCA / Trinseo Materials Finance Inc, Revolver, Materials 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 58.9                    
Fair Value, ending balance 106.3 [4],[18],[35]   58.9 [3],[17],[33]                
Investment, Identifier [Axis]: Trinseo Materials Operating SCA / Trinseo Materials Finance Inc, Revolver, Materials 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 58.8                    
Fair Value, ending balance 11.8 [4],[24],[35]   58.8 [3],[23],[33]                
Investment, Identifier [Axis]: Tropicana Products Inc, Revolver, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 74.4                    
Investment, Identifier [Axis]: Tropicana Products Inc, Revolver, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 10.4                    
Investment, Identifier [Axis]: Turnpoint Services Inc, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 12.8                    
Fair Value, ending balance 0.3 [4],[18]   12.8 [3],[17]                
Investment, Identifier [Axis]: Turnpoint Services Inc, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 1.6                    
Fair Value, ending balance 8.4 [4],[42]   1.6 [3],[23]                
Investment, Identifier [Axis]: Turnpoint Services Inc, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.5                    
Fair Value, ending balance 1.3 [4],[24]   2.5 [3],[23]                
Investment, Identifier [Axis]: Turnpoint Services Inc, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 2.5                    
Investment, Identifier [Axis]: USIC Holdings Inc, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28] 120.3                    
Fair Value, ending balance 121.5 [4],[18],[21],[42],[43],[47]   120.3 [3],[17],[19],[27],[28]                
Investment, Identifier [Axis]: USIC Holdings Inc, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 3.5                    
Fair Value, ending balance 8.2 [4],[18]   3.5 [3],[17]                
Investment, Identifier [Axis]: USIC Holdings Inc, Commercial & Professional Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.6                    
Fair Value, ending balance 5.5 [4],[24]   6.6 [3],[23]                
Investment, Identifier [Axis]: USIC Holdings Inc, Commercial & Professional Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 11.7                    
Fair Value, ending balance 6.9 [4],[24]   11.7 [3],[23]                
Investment, Identifier [Axis]: Ultra Electronics Holdings Ltd, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[33],[41],[46] 1.7                    
Fair Value, ending balance 1.7 [4],[35],[44],[45]   1.7 [3],[33],[41],[46]                
Investment, Identifier [Axis]: Ultra Electronics Holdings Ltd, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 62.8                    
Fair Value, ending balance 62.9 [4],[18],[35]   62.8 [3],[17],[33]                
Investment, Identifier [Axis]: Ultra Electronics Holdings Ltd, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 37.5                    
Fair Value, ending balance 40.7 [4],[18],[35]   37.5 [3],[17],[33]                
Investment, Identifier [Axis]: Ultra Electronics Holdings PLC, Private Equity, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 7.8                    
Fair Value, ending balance 7.9 [4],[18],[31],[35]   7.8 [3],[17],[30],[33]                
Investment, Identifier [Axis]: Ultra Electronics Holdings PLC, Private Equity, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 2.2                    
Fair Value, ending balance 2.2 [4],[18],[31],[35]   2.2 [3],[17],[30],[33]                
Investment, Identifier [Axis]: Valeo Foods Group Ltd, Food, Beverage & Tobacco 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 3.7                    
Fair Value, ending balance 4.0 [4],[18],[35]   3.7 [3],[17],[33]                
Investment, Identifier [Axis]: Valeo Foods Group Ltd, Food, Beverage & Tobacco 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.9                    
Fair Value, ending balance 3.0 [4],[24],[35]   2.9 [3],[23],[33]                
Investment, Identifier [Axis]: Vehicle Secured Funding Trust, ABF Equity, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[33] 23.1                    
Fair Value, ending balance 11.7 [4],[18],[31],[35]   23.1 [3],[17],[30],[33]                
Investment, Identifier [Axis]: Vehicle Secured Funding Trust, Term Loan, Financial Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 63.3                    
Fair Value, ending balance 31.7 [4],[18],[35]   63.3 [3],[17],[33]                
Investment, Identifier [Axis]: Veriforce LLC, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[19],[27],[28],[33] 36.9                    
Fair Value, ending balance 37.1 [4],[21],[43],[47]   36.9 [3],[19],[27],[28],[33]                
Investment, Identifier [Axis]: Veriforce LLC, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 16.9                    
Fair Value, ending balance 17.5 [4],[18]   16.9 [3],[17],[33]                
Investment, Identifier [Axis]: Veriforce LLC, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 4.7                    
Fair Value, ending balance 4.7 [4],[24]   4.7 [3],[23],[33]                
Investment, Identifier [Axis]: Veriforce LLC, Software & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 3.7                    
Fair Value, ending balance 3.7 [4],[24]   3.7 [3],[23],[33]                
Investment, Identifier [Axis]: Vermont Information Processing Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[42] 8.3                    
Investment, Identifier [Axis]: Vermont Information Processing Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 9.6                    
Investment, Identifier [Axis]: Vermont Information Processing Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 2.9                    
Investment, Identifier [Axis]: Version1 Software Ltd, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 2.1                    
Fair Value, ending balance 2.1 [4],[18],[35]   2.1 [3],[17],[33]                
Investment, Identifier [Axis]: Version1 Software Ltd, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 12.3                    
Fair Value, ending balance 13.0 [4],[24],[35]   12.3 [3],[23],[33]                
Investment, Identifier [Axis]: VetCor Professional Practices LLC, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 67.9                    
Fair Value, ending balance 67.7 [4],[18],[42],[44]   67.9 [3],[17],[41]                
Investment, Identifier [Axis]: VetCor Professional Practices LLC, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 8.4                    
Fair Value, ending balance 8.4 [4],[18],[42]   8.4 [3],[17]                
Investment, Identifier [Axis]: VetCor Professional Practices LLC, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.7                    
Fair Value, ending balance 13.5 [4],[18]   6.7 [3],[23]                
Investment, Identifier [Axis]: VetCor Professional Practices LLC, Health Care Equipment & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 34.3                    
Fair Value, ending balance 6.7 [4],[24]   34.3 [3],[23]                
Investment, Identifier [Axis]: VetCor Professional Practices LLC, Health Care Equipment & Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 20.8                    
Investment, Identifier [Axis]: Vietjet Aviation JSC, Term Loan, Transportation 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 32.5                    
Investment, Identifier [Axis]: Vietjet Aviation JSC, Term Loan, Transportation 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 32.5                    
Investment, Identifier [Axis]: Vitu, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[21],[43],[47] 55.7                    
Investment, Identifier [Axis]: Vitu, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24] 9.1                    
Investment, Identifier [Axis]: Vytalogy Wellness LLC (fka Jarrow Formulas Inc), Household & Personal Products                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[20],[27],[28],[41] 109.9                    
Fair Value, ending balance 107.8 [4],[18],[22],[43],[44]   109.9 [3],[17],[19],[20],[27],[28],[41]                
Investment, Identifier [Axis]: Warren Resources Inc                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 18.8 18.8                
Gross Additions [12]     0.0                
Gross Reductions [14]     (19.0)                
Net Realized Gain (Loss)     0.5                
Net Change in Unrealized Appreciation (Depreciation)     (0.3)                
Fair Value, ending balance     0.0                
Investment Income [16]     1.0                
PIK Income [16]     0.1                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Warren Resources Inc, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.0 12.3 12.3                
Gross Additions [12]     0.0                
Gross Reductions [14]     (10.7)                
Net Realized Gain (Loss)     (2.1)                
Net Change in Unrealized Appreciation (Depreciation)     0.5                
Fair Value, ending balance     0.0                
Investment Income [16]     0.0                
PIK Income [16]     0.0                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Warren Resources Inc, Energy                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 21.0                    
Fair Value, ending balance 20.8 [4],[18]   21.0 [3],[17]                
Investment, Identifier [Axis]: Waste Services Group Pty Ltd, Commercial & Professional Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 30.7                    
Investment, Identifier [Axis]: Waste Services Group Pty Ltd, Commercial & Professional Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 6.9                    
Investment, Identifier [Axis]: Wealth Enhancement Group LLC, Financial Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.0                    
Fair Value, ending balance 1.3 [4],[18]   0.0 [3],[17]                
Investment, Identifier [Axis]: Wealth Enhancement Group LLC, Financial Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 1.0                    
Fair Value, ending balance 2.8 [4],[24]   1.0 [3],[17]                
Investment, Identifier [Axis]: Wealth Enhancement Group LLC, Financial Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 2.8                    
Fair Value, ending balance 20.1 [4],[24]   2.8 [3],[23]                
Investment, Identifier [Axis]: Wealth Enhancement Group LLC, Financial Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 0.4                    
Fair Value, ending balance [3],[23]     0.4                
Investment, Identifier [Axis]: Wealth Enhancement Group LLC, Financial Services 5                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 19.9                    
Fair Value, ending balance [3],[23]     19.9                
Investment, Identifier [Axis]: Weber-Stephen Products LLC, Revolver, Consumer Discretionary Distribution & Retail 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[33] 26.4                    
Fair Value, ending balance 72.1 [4],[18],[35]   26.4 [3],[17],[33]                
Investment, Identifier [Axis]: Weber-Stephen Products LLC, Revolver, Consumer Discretionary Distribution & Retail 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 57.5                    
Fair Value, ending balance 11.9 [4],[24],[35]   57.5 [3],[23],[33]                
Investment, Identifier [Axis]: Wittur Holding GmbH                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 54.1                    
Gross Additions [11] 1.7                    
Gross Reductions [13] 0.0                    
Net Realized Gain (Loss) 0.0                    
Net Change in Unrealized Appreciation (Depreciation) 3.0                    
Fair Value, ending balance 58.8   54.1                
Investment Income [15] 0.3                    
PIK Income [15] 0.8                    
Fee income [15] 0.0                    
Dividend and Other Income [15] 0.0                    
Investment, Identifier [Axis]: Wittur Holding GmbH 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 54.1 0.0 0.0                
Gross Additions [12]     57.7                
Gross Reductions [14]     0.0                
Net Realized Gain (Loss)     0.0                
Net Change in Unrealized Appreciation (Depreciation)     (3.6)                
Fair Value, ending balance     54.1                
Investment Income [16]     0.1                
PIK Income [16]     2.6                
Fee income [16]     0.0                
Dividend and Other Income [16]     0.0                
Investment, Identifier [Axis]: Wittur Holding GmbH, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32],[33] 54.1                    
Fair Value, ending balance 58.8 [4],[18],[34],[35]   54.1 [3],[17],[32],[33]                
Investment, Identifier [Axis]: Wittur Holding GmbH, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 10.9 0.0 0.0                
Gross Additions 0.0 [11]   8.0 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 3.2   2.9                
Fair Value, ending balance 14.1   10.9                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Wittur Holding GmbH, Common Stock, Capital Goods                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32],[33] 10.9                    
Fair Value, ending balance 14.1 [4],[18],[31],[34],[35]   10.9 [3],[17],[30],[32],[33]                
Investment, Identifier [Axis]: Woolpert Inc, Capital Goods 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 0.6                    
Fair Value, ending balance 78.8 [4],[18],[21],[43],[47]   0.6 [3],[17]                
Investment, Identifier [Axis]: Woolpert Inc, Capital Goods 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[19],[27],[28] 73.5                    
Fair Value, ending balance 18.6 [4],[24]   73.5 [3],[17],[19],[27],[28]                
Investment, Identifier [Axis]: Woolpert Inc, Capital Goods 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 17.9                    
Fair Value, ending balance 31.6 [4],[24]   17.9 [3],[23]                
Investment, Identifier [Axis]: Woolpert Inc, Capital Goods 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 31.6                    
Fair Value, ending balance [3],[23]     31.6                
Investment, Identifier [Axis]: Worldwise Inc                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 19.1 0.0 0.0                
Gross Additions 0.3 [11]   19.1 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) 0.0   0.0                
Fair Value, ending balance 19.4   19.1                
Investment Income 0.2 [15]   0.1 [16]                
PIK Income 0.2 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Worldwise Inc, Common Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 0.7 0.0 0.0                
Gross Additions 0.0 [11]   0.6 [12]                
Gross Reductions 0.0 [13]   0.0 [14]                
Net Realized Gain (Loss) 0.0   0.0                
Net Change in Unrealized Appreciation (Depreciation) (0.5)   0.1                
Fair Value, ending balance 0.2   0.7                
Investment Income 0.0 [15]   0.0 [16]                
PIK Income 0.0 [15]   0.0 [16]                
Fee income 0.0 [15]   0.0 [16]                
Dividend and Other Income 0.0 [15]   0.0 [16]                
Investment, Identifier [Axis]: Worldwise Inc, Common Stock, Household & Personal Products                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[30],[32] 0.7                    
Fair Value, ending balance 0.2 [4],[18],[31],[34]   0.7 [3],[17],[30],[32]                
Investment, Identifier [Axis]: Worldwise Inc, Household & Personal Products 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[32] 19.1                    
Fair Value, ending balance 19.4 [4],[18],[34]   19.1 [3],[17],[32]                
Investment, Identifier [Axis]: Worldwise Inc, Household & Personal Products 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[32] 1.7                    
Fair Value, ending balance 1.7 [4],[24],[34]   1.7 [3],[23],[32]                
Investment, Identifier [Axis]: Zellis Holdings Ltd, Software & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 7.9                    
Fair Value, ending balance [3],[23],[33]     7.9                
Investment, Identifier [Axis]: Zellis Holdings Ltd, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[18],[35] 3.0                    
Investment, Identifier [Axis]: Zellis Holdings Ltd, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, ending balance [4],[24],[35] 5.0                    
Investment, Identifier [Axis]: Zendesk Inc, Software & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[41] 60.0                    
Fair Value, ending balance 59.9 [4],[18],[42],[44]   60.0 [3],[17],[41]                
Investment, Identifier [Axis]: Zendesk Inc, Software & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 14.7                    
Fair Value, ending balance 14.7 [4],[24]   14.7 [3],[23]                
Investment, Identifier [Axis]: Zendesk Inc, Software & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 6.0                    
Fair Value, ending balance 6.0 [4],[24]   6.0 [3],[23]                
Investment, Identifier [Axis]: Zeus Industrial Products Inc, Health Care Equipment & Services 1                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 83.5                    
Fair Value, ending balance 83.3 [4],[18],[42]   83.5 [3],[17]                
Investment, Identifier [Axis]: Zeus Industrial Products Inc, Health Care Equipment & Services 2                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17] 5.5                    
Fair Value, ending balance 5.5 [4],[18]   5.5 [3],[17]                
Investment, Identifier [Axis]: Zeus Industrial Products Inc, Health Care Equipment & Services 3                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 11.6                    
Fair Value, ending balance 11.6 [4],[24]   11.6 [3],[23]                
Investment, Identifier [Axis]: Zeus Industrial Products Inc, Health Care Equipment & Services 4                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23] 10.2                    
Fair Value, ending balance 10.2 [4],[24]   10.2 [3],[23]                
Investment, Identifier [Axis]: athenahealth Inc, Preferred Stock                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance 361.3 $ 252.6 252.6                
Gross Additions 9.5 [5]   86.5 [6]                
Gross Reductions (20.1) [7]   0.0 [8]                
Net Realized Gain (Loss) 0.4   0.0                
Net Change in Unrealized Appreciation (Depreciation) 2.8   22.2                
Fair Value, ending balance 353.9   361.3                
Investment Income 0.0 [9]   0.0 [10]                
PIK Income 9.5 [9]   31.9 [10]                
Fee income 0.0 [9]   0.0 [10]                
Dividend and Other Income 0.0 [9]   0.0 [10]                
Investment, Identifier [Axis]: athenahealth Inc, Preferred Stock, Health Care Equipment & Services                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[17],[26] 361.3                    
Fair Value, ending balance 353.9 [4],[18],[29]   361.3 [3],[17],[26]                
Investment, Identifier [Axis]: iNova Pharmaceuticals (Australia) Pty Limited, Pharmaceuticals, Biotechnology & Life Sciences                      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]                      
Fair Value, beginning balance [3],[23],[33] 2.7                    
Fair Value, ending balance $ 2.9 [4],[24],[35]   $ 2.7 [3],[23],[33]                
[1] Security may be an obligation of one or more entities affiliated with the named company.
[2] Security may be an obligation of one or more entities affiliated with the named company.
[3] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.
[4] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.
[5] Gross additions include increases in the cost basis of investments resulting from new portfolio investments, PIK interest, the amortization of unearned income, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company into this category from a different category.
[6] Gross additions include increases in the cost basis of investments resulting from new portfolio investments, PIK interest, the amortization of unearned income, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company into this category from a different category.
[7] Gross reductions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company out of this category into a different category.
[8] Gross reductions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company out of this category into a different category.
[9] Interest, PIK, Fee and Dividend and Other income presented for the three months ended March 31, 2025.
[10] Interest, PIK, Fee and Dividend and Other income presented for the full year ended December 31, 2024.
[11] Gross additions include increases in the cost basis of investments resulting from new portfolio investments, PIK interest, the amortization of unearned income, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company into this category from a different category.
[12] Gross additions include increases in the cost basis of investments resulting from new portfolio investments, PIK interest, the amortization of unearned income, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company into this category from a different category.
[13] Gross reductions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company out of this category into a different category.
[14] Gross reductions include decreases in the cost basis of investments resulting from principal collections related to investment repayments or sales, the exchange of one or more existing securities for one or more new securities and the movement of an existing portfolio company out of this category into a different category.
[15] Interest, PIK, Fee and Dividend and Other income presented for the three months ended March 31, 2025.
[16] Interest, PIK, Fee and Dividend and Other income presented for the full year ended December 31, 2024.
[17] Security or portion thereof is pledged as collateral supporting the amounts outstanding under the Senior Secured Revolving Credit Facility (see Note 9).
[18] Security or portion thereof is pledged as collateral supporting the amounts outstanding under the Senior Secured Revolving Credit Facility (see Note 9).
[19] Security or portion thereof held within Darby Creek LLC and is pledged as collateral supporting the amounts outstanding under a revolving credit facility with Deutsche Bank AG, New York Branch (see Note 9).
[20] Security or portion thereof held within CCT Tokyo Funding LLC and pledged as collateral supporting the amounts outstanding under the revolving credit facility with Sumitomo Mitsui Banking Corporation (see Note 9).
[21] Security or portion thereof held within Darby Creek LLC and is pledged as collateral supporting the amounts outstanding under a revolving credit facility with Deutsche Bank AG, New York Branch (see Note 9).
[22] Security or portion thereof held within CCT Tokyo Funding LLC and pledged as collateral supporting the amounts outstanding under the revolving credit facility with Sumitomo Mitsui Banking Corporation (see Note 9).
[23] Security is an unfunded commitment. Reflects the stated spread at the time of commitment, but may not be the actual rate received upon funding.
[24] Security is an unfunded commitment. Reflects the stated spread at the time of commitment, but may not be the actual rate received upon funding.
[25] The Company held this investment as of December 31, 2023 but it was not deemed to be an “affiliated person” of the portfolio company as of December 31, 2023. Transfers in or out have been presented at amortized cost.
[26] Under the Investment Company Act of 1940, as amended, the Company generally is deemed to be an “affiliated person” of a portfolio company if it owns 5% or more of the portfolio company’s voting securities and generally is deemed to “control” a portfolio company if it owns more than 25% of the portfolio company’s voting securities or it has the power to exercise control over the management or policies of such portfolio company. As of December 31, 2024, the Company held investments in portfolio companies of which it is deemed to be an “affiliated person” but is not deemed to “control”. The following table presents certain information with respect to investments in portfolio companies of which the Company was deemed to be an affiliated person for the year ended December 31, 2024:
Portfolio Company
Fair Value at December 31, 2023
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at December 31, 2024
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—First Lien
48Forty Solutions LLC(4)
$— $184.4 $(10.7)$(0.1)$(25.1)$148.5 $16.0 $4.4 $— $— 
48Forty Solutions LLC(4)
— 8.8 (4.2)— (1.6)3.0 1.0 — — — 
Affordable Care Inc35.6 6.6 (7.4)— 0.4 35.2 4.2 — — — 
Affordable Care Inc7.3 14.9 (0.1)— 0.1 22.2 1.8 — 0.1 — 
Belk Inc13.2 — (16.7)(18.9)22.4 — (0.9)— — — 
Belk Inc20.0 — (21.9)0.1 1.8 — 1.9 — — — 
Belk Inc— 30.0 (0.6)— 0.1 29.5 2.0 — 0.9 — 
Constellis Holdings LLC15.1 0.2 (15.1)0.3 (0.5)— 1.6 — 0.1 — 
Galaxy Universal LLC86.4 — (0.8)— 0.7 86.3 10.2 — — — 
Galaxy Universal LLC18.1 — — — 0.4 18.5 2.0 — — — 
One Call Care Management Inc4.2 — — — 0.5 4.7 0.6 — — — 
Portfolio Company
Fair Value at December 31, 2023
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at December 31, 2024
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—Second Lien
 Belk Inc $— $— $(0.7)$(3.5)$4.2 $— $— $— $— $— 
 Constellis Holdings LLC 9.0 0.3 (9.9)(3.5)4.1 — 1.7 — — — 
 Constellis Holdings LLC
— 6.8 — — 0.2 7.0 0.1 — — — 
Other Senior Secured Debt
 One Call Care Management Inc
20.6 2.7 — — 1.8 25.1 — 2.4 — — 
Asset Based Finance
Accelerator Investments Aggregator LP, Private Equity4)
2.5 — (1.6)(0.1)0.1 0.9 — — — — 
Altavair AirFinance, Private Equity
133.9 — (7.4)— 1.7 128.2 — — — 15.5 
GreenSky Holdings LLC, ABF Equity— 10.7 — — 4.2 14.9 — — — — 
GreenSky Holdings LLC, ABF Equity— 20.6 — — 1.7 22.3 — — — — 
GreenSky Holdings LLC, Term Loan— 33.5 — — — 33.5 — 2.4 — — 
Home Partners JV 2, Structured Mezzanine11.4 1.4 (12.8)— — — — 1.0 — — 
Home Partners JV 2, ABF Equity0.2 — (0.2)— — — — — — — 
Home Partners JV 2, ABF Equity4.2 — (4.1)(0.3)0.2 — — — — — 
Equity/Other
48Forty Solutions LLC, Common Stock— — — — — — — — — — 
Affordable Care Inc, Preferred Stock50.0 19.8 — — 3.3 73.1 — 6.4 — — 
athenahealth Inc, Preferred Stock252.6 86.5 — — 22.2 361.3 — 31.9 — — 
Belk Inc, Common Stock— — — — — — — — — — 
Belk Inc, Common Stock— 17.6 — — 9.5 27.1 — — — — 
Borden (New Dairy Opco), Common Stock(4)
11.2 — (4.9)— (6.3)— — — — — 
Constellis Holdings LLC, Private Equity— — — — — — — — — — 
Constellis Holdings LLC, Preferred Equity— 3.2 — — 0.2 3.4 — — — — 
Fronton BV, Common Stock1.8 — (1.7)1.7 (1.8)— — — — — 
Galaxy Universal LLC, Common Stock0.5 — — — 48.7 49.2 — — — — 
Galaxy Universal LLC, Trade Claim1.0 — — — 0.9 1.9 — — — — 
Galaxy Universal LLC, Preferred Stock5.5 0.9 — — 0.8 7.2 — 0.5 — — 
One Call Care Management Inc, Preferred Stock A18.5 — — — 2.2 20.7 — — — — 
One Call Care Management Inc, Common Stock1.9 — — — — 1.9 — — — — 
One Call Care Management Inc, Preferred Stock B7.7 2.4 — — 2.1 12.2 — 0.6 — — 
Proserv Acquisition LLC, Class A Common Units3.5 — (7.3)(26.2)30.0 — — — — — 
Proserv Acquisition LLC, Class A Preferred Units9.5 — (2.3)— (5.0)2.2 — — — — 
ThermaSys Corp, Common Stock— — — (10.2)10.2 — — — — — 
Total$745.4 $451.3 $(130.4)$(60.7)$134.4 $1,140.0 $42.2 $49.6 $1.1 $15.5 
[27] Security or portion thereof held within Ambler Funding LLC and is pledged as collateral supporting the amounts outstanding under the revolving credit facility with Ally Bank (see Note 9).
[28] Security or portion thereof held within Meadowbrook Run LLC and is pledged as collateral supporting the amounts outstanding under a revolving credit facility with Morgan Stanley Senior Funding, Inc. (see Note 9).
[29] Under the Investment Company Act of 1940, as amended, the Company generally is deemed to be an “affiliated person” of a portfolio company if it owns 5% or more of the portfolio company’s voting securities and generally is deemed to “control” a portfolio company if it owns more than 25% of the portfolio company’s voting securities or it has the power to exercise control over the management or policies of such portfolio company. As of March 31, 2025, the Company held investments in portfolio companies of which it is deemed to be an “affiliated person” but is not deemed to “control”. The following table presents certain information with respect to investments in portfolio companies of which the Company was deemed to be an affiliated person for the three months ended March 31, 2025:
Portfolio Company
Fair Value at December 31, 2024
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at March 31, 2025
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—First Lien
48Forty Solutions LLC$148.5 $3.8 $— $— $(16.5)$135.8 $1.0 $3.8 $— $— 
48Forty Solutions LLC3.0 — (0.6)— (0.9)1.5 0.1 — — — 
Affordable Care Inc35.2 1.5 (1.1)— 0.2 35.8 0.7 0.3 — — 
Affordable Care Inc22.2 0.2 — — — 22.4 0.4 0.2 — — 
Belk Inc29.5 — (1.8)— 0.1 27.8 1.0 — — — 
Galaxy Universal LLC86.3 — (0.3)— — 86.0 2.4 — 0.2 — 
Galaxy Universal LLC18.5 1.9 — — (0.4)20.0 0.5 — 0.1 — 
Galaxy Universal LLC— 45.5 — — (0.9)44.6 1.1 — 2.0 — 
Galaxy Universal LLC— 37.5 — — — 37.5 0.1 — 1.1 — 
One Call Care Management Inc4.7 — — — — 4.7 0.2 — — — 
Senior Secured Loans—Second Lien
 Constellis Holdings LLC 7.0 0.5 — — — 7.5 0.3 0.2 — — 
Other Senior Secured Debt
 One Call Care Management Inc 25.1 0.1 — — 0.1 25.3 0.1 0.6 — — 
Asset Based Finance
Accelerator Investments Aggregator LP, ABF Equity 0.9 — — — — 0.9 — — — — 
Altavair AirFinance, ABF Equity 128.2 — (1.6)— (0.1)126.5 — — — 8.9 
GreenSky Holdings LLC, ABF Equity14.9 — — — (0.8)14.1 — — — — 
GreenSky Holdings LLC, ABF Equity22.3 2.6 — — 1.9 26.8 — — — — 
GreenSky Holdings LLC, Term Loan33.5 1.6 — — — 35.1 — 0.7 — — 
Equity/Other
48Forty Solutions LLC, Common Stock— — — — — — — — — — 
Affordable Care Inc, Preferred Stock73.1 1.9 — — (0.1)74.9 — 2.0 — — 
athenahealth Inc, Preferred Stock361.3 9.5 (20.1)0.4 2.8 353.9 — 9.5 — — 
Belk Inc, Common Stock27.1 4.2 — — 4.2 35.5 — — — — 
Constellis Holdings LLC, Private Equity— — — — — — — — — — 
Constellis Holdings LLC, Preferred Equity3.4 — — — (1.0)2.4 — — — — 
Galaxy Universal LLC, Common Stock49.2 — (30.4)8.5 (8.5)18.8 — — — — 
Galaxy Universal LLC, Trade Claim1.9 — — — — 1.9 — — — — 
Galaxy Universal LLC, Preferred Stock7.2 — — — (0.1)7.1 — 0.1 — — 
Portfolio Company
Fair Value at December 31, 2024
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at March 31, 2025
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
One Call Care Management Inc, Preferred Stock A$20.7 $— $— $— $(0.4)$20.3 $— $— $— $— 
One Call Care Management Inc, Common Stock1.9 — — — — 1.9 — — — — 
One Call Care Management Inc, Preferred Stock B12.2 0.1 — — 0.1 12.4 0.1 0.2 — — 
Proserv Acquisition LLC, Class A Preferred Units2.2 — — — — 2.2 — — — — 
Total$1,140.0 $110.9 $(55.9)$8.9 $(20.3)$1,183.6 $8.0 $17.6 $3.4 $8.9 
[30] Security is non-income producing.
[31] Security is non-income producing.
[32] Under the Investment Company Act of 1940, as amended, the Company generally is deemed to “control” a portfolio company if it owns more than 25% of the portfolio company’s voting securities or it has the power to exercise control over the management or policies of such portfolio company. As of December 31, 2024, the Company held investments in portfolio companies of which it is deemed to be an “affiliated person” and deemed to “control”. During the year ended December 31, 2024, the Company disposed of investments in portfolio companies of which it was deemed to be an “affiliated person” and deemed to “control”. The following table presents certain information with respect to investments in portfolio companies of which the Company was deemed to be an affiliated person and deemed to control for the year ended December 31, 2024:
Portfolio Company
Fair Value at December 31, 2023
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at December 31, 2024
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—First Lien
ATX Networks Corp$65.1 $36.3 $(101.4)$— $— $— $1.8 $5.8 $— $— 
ATX Networks Corp— 36.4 — — 0.6 37.0 — 0.8 — — 
ATX Networks Corp— 15.3 — — — 15.3 — 1.0 — — 
ATX Networks Corp— 50.6 — — — 50.6 — 4.0 — — 
Gracent LLC24.5 4.8 — — 0.3 29.6 — 4.8 — — 
H.M. Dunn Co., Inc., L+87535.8 — (1.0)— — 34.8 4.1 — — — 
H.M. Dunn Co., 15%1.0 2.4 — — — 3.4 0.2 — — — 
Kellermeyer Bergensons Services LLC— — — — — — — — — — 
Kellermeyer Bergensons Services LLC— 198.9 (1.4)— 4.1 201.6 — 17.2 — — 
Kellermeyer Bergensons Services LLC— 88.2 — — (0.5)87.7 — 9.3 — — 
NCI Inc32.2 1.0 (1.1)— — 32.1 2.1 2.1 — — 
Production Resource Group LLC168.6 30.0 (0.7)— (2.0)195.9 13.4 20.9 5.3 — 
Production Resource Group LLC0.1 0.1 — — 0.1 0.3 — — — — 
Production Resource Group LLC63.6 6.8 (1.6)— (1.1)67.7 5.0 4.3 — — 
Production Resource Group LLC34.8 3.0 (0.8)— 0.2 37.2 3.0 2.4 — — 
Production Resource Group LLC— 105.3 (1.0)— 3.1 107.4 3.0 5.6 4.0 — 
Warren Resources Inc18.8 — (19.0)0.5 (0.3)— 1.0 0.1 — — 
Wittur Holding GmbH— 57.7 — — (3.6)54.1 0.1 2.6 — — 
Worldwise Inc— 19.1 — — — 19.1 0.1 — — — 
Senior Secured Loans—Second Lien
Quoizel, LLC6.5 0.6 — — — 7.1 0.2 0.6 — — 
Quoizel, LLC6.8 0.6 — — — 7.4 0.3 0.6 — — 
Other Senior Secured Debt
JW Aluminum Co77.1 0.2 — — (0.7)76.6 8.1 — — — 
Subordinated Debt
ATX Networks Corp32.9 1.9 — — (1.9)32.9 — 0.7 — — 
Portfolio Company
Fair Value at December 31, 2023
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at December 31, 2024
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Asset Based Finance
801 5th Ave, Seattle, Structure Mezzanine$52.7 $2.0 $— $— $(0.2)$54.5 $5.1 $1.8 $— $— 
801 5th Ave, Seattle, ABF Equity— — — — — — — — — — 
Abacus JV, ABF Equity48.5 — (11.3)0.3 (12.9)24.6 — — — — 
Australis Maritime, Common Stock35.8 — (23.8)— (0.7)11.3 — — — 0.3 
Australis Maritime II, ABF Equity12.2 10.4 (1.6)— (1.2)19.8 — — — 2.2 
Avenue One PropCo, ABF Equity38.8 — (37.9)— (0.9)— — — — — 
Avenue One PropCo, ABF Equity— 10.3 — — (0.1)10.2 — — — — 
Avenue One PropCo, Term Loan— 32.3 — — — 32.3 0.1 1.7 — — 
Avida Holding AB, Common Stock42.9 25.0 — — (7.5)60.4 — — — — 
Avida Holding AB, Subordinated Bond1.5 — — — (0.2)1.3 0.2 — — — 
Capital Automotive LP, ABF Equity32.4 — (1.1)— 1.6 32.9 — — — 2.9 
Capital Automotive LP, Structured Mezzanine41.5 0.1 (1.4)— (0.1)40.1 4.6 — — — 
Discover Financial Services, Subordinated Loan— 38.8 — — — 38.8 1.3 — — — 
Discover Financial Services, ABF Equity— 20.9 — — 0.8 21.7 — — — — 
Kilter Finance, Preferred Stock99.7 1.5 (15.8)0.8 (0.8)85.4 12.0 — — — 
Kilter Finance, ABF Equity0.5 — — — — 0.5 — — — — 
KKR Altitude II Offshore Aggregator LP, Partnership Interest65.6 74.2 — — 6.9 146.7 — — — 6.6 
KKR Central Park Leasing Aggregator L.P., Partnership Interest15.3 — — — 0.5 15.8 — — — — 
KKR Chord IP Aggregator LP, Partnership Interest99.9 — (120.3)30.7 (10.2)0.1 — — — 0.5 
KKR Rocket Loans Aggregator LLC, Partnership Interest8.3 — (4.3)— 0.3 4.3 — — — 0.3 
KKR Zeno Aggregator LP (K2 Aviation), Partnership Interest11.8 — (9.0)0.3 4.1 7.2 — — — 2.6 
My Community Homes PropCo 2, ABF Equity78.8 — (81.1)— 2.3 — — — — — 
My Community Homes PropCo 2, ABF Equity— 20.3 — — (4.7)15.6 — — — — 
My Community Homes PropCo 2, Term Loan— 64.4 — — — 64.4 0.1 3.7 — — 
Prime St LLC, ABF Equity— 1.6 — — (1.6)— — — — — 
Prime St LLC, Structured Mezzanine33.1 3.8 — — (9.3)27.6 3.2 3.5 — — 
Roemanu LLC (FKA Toorak Capital Partners LLC), ABF Equity241.0 — — — (2.1)238.9 — — — 4.8 
TDC LLP, Preferred Equity27.8 22.2 (11.5)0.3 (2.0)36.8 1.8 — — — 
TDC LLP, Preferred Equity2.0 — — — (0.1)1.9 — — — — 
Credit Opportunities Partners JV, LLC
Credit Opportunities Partners JV, LLC1,396.9 — — — (33.6)1,363.3 — — — 212.3 
Equity/Other
ATX Networks Corp, Common Stock25.9 — — — (25.9)— — — — — 
Portfolio Company
Fair Value at December 31, 2023
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at December 31, 2024
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
ATX Networks Corp, Class B-1 Common Stock$2.5 $— $— $— $(2.5)$— $— $— $— $— 
ATX Networks Corp, Class B-2 Common Stock0.8 — — — (0.8)— — — — — 
Borden (New Dairy Opco), Common Stock— 4.9 (5.3)0.4 18.4 18.4 — — — — 
Gracent LLC, Preferred Stock A— — — (8.0)8.0 — — — — — 
Gracent LLC, Preferred Stock B— — — — — — — — — — 
Gracent LLC, Class A Common Stock— — — — — — — — — — 
Gracent LLC, Preferred Equity3.8 — — — 1.2 5.0 — — — — 
HM Dunn Co Inc, Preferred Stock, Series A25.1 — — — (25.0)0.1 — — — — 
HM Dunn Co Inc, Preferred Stock, Series B— — — — — — — — — — 
JW Aluminum Co, Common Stock2.5 — — — — 2.5 — — — — 
JW Aluminum Co, Preferred Stock148.7 — — — 3.6 152.3 — — — — 
Kellermeyer Bergensons Services LLC, Common Stock— — — — — — — — — — 
Kellermeyer Bergensons Services LLC, Preferred Stock— 48.3 — — (33.2)15.1 — — — — 
NCI Inc, Class A-1 Common Stock— — — — — — — — — — 
NCI Inc, Class B-1 Common Stock— — — — — — — — — — 
NCI Inc, Class C Common Stock19.7 — — — 13.4 33.1 — — — — 
NCI Inc, Class I-1 Common Stock— — — — — — — — — — 
Production Resource Group LLC, Preferred Stock, Series A PIK120.7 — — — (53.5)67.2 — — — — 
Production Resource Group LLC, Preferred Stock, Series B PIK— — — — — — — — — — 
Quoizel, LLC, Common Stock10.2 — — — (4.1)6.1 — — — — 
Quorum Health Corp, Trade Claim0.9 — — — — 0.9 — — — — 
Quorum Health Corp, Trust Initial Funding Units0.1 — — — — 0.1 — — — — 
Quorum Health Corp, Private Equity7.7 3.7 — — (1.3)10.1 — — — — 
Warren Resources Inc, Common Stock12.3 — (10.7)(2.1)0.5 — — — — — 
Wittur Holding GmbH, Common Stock— 8.0 — — 2.9 10.9 — — — — 
Worldwise Inc, Common Stock— 0.6 — — 0.1 0.7 — — — — 
Total$3,335.7 $1,052.5 $(463.1)$23.2 $(171.6)$3,776.7 $70.8 $93.5 $9.3 $232.5 
[33] The investment is not a qualifying asset under the Investment Company Act of 1940, as amended. A business development company may not acquire any asset other than qualifying assets, unless, at the time the acquisition is made, qualifying assets represent at least 70% of the company’s total assets. As of December 31, 2024, 73.2% of the Company’s total assets represented qualifying assets.
[34] Under the Investment Company Act of 1940, as amended, the Company generally is deemed to “control” a portfolio company if it owns more than 25% of the portfolio company’s voting securities or it has the power to exercise control over the management or policies of such portfolio company. As of March 31, 2025, the Company held investments in portfolio companies of which it is deemed to be an “affiliated person” and deemed to “control”. The following table presents certain information with respect to investments in portfolio companies of which the Company was deemed to be an affiliated person and deemed to control for the three months ended March 31, 2025:
Portfolio Company
Fair Value at December 31, 2024
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at March 31, 2025
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—First Lien
Alacrity Solutions Group LLC$— $10.2 $— $— $0.1 $10.3 $0.1 $— $— $— 
Alacrity Solutions Group LLC— 0.1 — — — 0.1 — — — — 
ATX Networks Corp37.0 1.1 — — (0.1)38.0 (0.7)1.0 — — 
ATX Networks Corp15.3 0.4 — — — 15.7 0.1 0.4 — — 
ATX Networks Corp50.6 1.5 — — — 52.1 — 1.4 — — 
Gracent LLC29.6 1.2 — — (0.2)30.6 0.2 1.0 — — 
HM Dunn Co Inc34.8 — (0.2)— (1.5)33.1 0.9 — — — 
HM Dunn Co Inc3.4 1.0 — — (0.2)4.2 0.1 — — — 
Kellermeyer Bergensons Services LLC201.6 5.4 (0.5)— (0.3)206.2 — 5.2 — — 
Kellermeyer Bergensons Services LLC87.7 3.0 — — (6.2)84.5 — 2.9 — — 
NCI Inc32.1 — (0.3)— — 31.8 0.9 — — — 
Production Resource Group LLC195.9 6.9 — — 0.1 202.9 1.4 6.9 — — 
Production Resource Group LLC0.3 0.1 — — (0.1)0.3 — — — — 
Production Resource Group LLC67.7 1.6 — — 0.1 69.4 0.5 1.6 — — 
Production Resource Group LLC37.2 0.9 — — (0.1)38.0 0.2 0.9 — — 
Production Resource Group LLC107.4 2.5 — — 0.1 110.0 0.6 2.5 — — 
Production Resource Group LLC— 9.6 — — 0.7 10.3 0.1 — — — 
Wittur Holding GmbH54.1 1.7 — — 3.0 58.8 0.3 0.8 — — 
Worldwise Inc19.1 0.3 — — — 19.4 0.2 0.2 — — 
Portfolio Company
Fair Value at December 31, 2024
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at March 31, 2025
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Senior Secured Loans—Second Lien
Quoizel, LLC$7.1 $— $— $— $— $7.1 $0.2 $— $— $— 
Quoizel, LLC7.4 — — — — 7.4 0.2 — — — 
Other Senior Secured Debt
JW Aluminum Co 76.6 — (76.4)0.3 (0.5)— 1.9 — — — 
Subordinated Debt
Accuride Corp— 4.2 — — 3.4 7.6 — — — — 
Alacrity Solutions Group LLC— 3.4 — — — 3.4 — — — — 
ATX Networks Corp32.9 — — — 2.7 35.6 — — — — 
Asset Based Finance
801 5th Ave, Seattle, Structure Mezzanine54.5 0.1 — — 0.9 55.5 1.5 0.5 — — 
801 5th Ave, Seattle, ABF Equity— — — — — — — — — — 
Abacus JV, ABF Equity24.6 — (27.0)0.7 2.2 0.5 — — — — 
Australis Maritime, Common Stock11.3 — (0.3)— 0.1 11.1 — — — — 
Australis Maritime II, ABF Equity19.8 — (3.1)— (0.2)16.5 — — — 0.6 
Avenue One PropCo, ABF Equity10.2 — — — (1.3)8.9 — — — — 
Avenue One PropCo, Term Loan32.3 0.6 — — — 32.9 — 0.6 — — 
Avida Holding AB, Common Stock60.4 — — — (0.9)59.5 — — — — 
Avida Holding AB, Subordinated Bond1.3 — — — 0.2 1.5 — — — — 
Capital Automotive LP, ABF Equity32.9 — (17.3)6.8 (5.4)17.0 — — — 0.5 
Capital Automotive LP, Structured Mezzanine40.1 — (20.4)0.1 (0.1)19.7 1.1 — — — 
Discover Financial Services, Subordinated Loan38.8 — (3.1)— — 35.7 1.4 — — — 
Discover Financial Services, ABF Equity21.7 — (1.2)— — 20.5 — — — 1.1 
Kilter Finance, Preferred Stock85.4 — (15.7)— — 69.7 2.3 — — — 
Kilter Finance, ABF Equity0.5 — — — — 0.5 — — — — 
KKR Altitude II Offshore Aggregator LP, Partnership Interest146.7 — (37.7)3.3 (2.0)110.3 — — — 3.5 
KKR Central Park Leasing Aggregator L.P., Partnership Interest15.8 — — — 0.2 16.0 — — — — 
KKR Chord IP Aggregator LP, Partnership Interest0.1 — — — — 0.1 — — — 0.1 
KKR Rocket Loans Aggregator LLC, Partnership Interest4.3 — (0.7)— — 3.6 — — — — 
KKR Zeno Aggregator LP (K2 Aviation), Partnership Interest7.2 — (2.9)0.3 (3.0)1.6 — — — 4.0 
My Community Homes PropCo 2, ABF Equity15.6 — — — (4.9)10.7 — — — — 
My Community Homes PropCo 2, Term Loan64.4 1.2 — — — 65.6 — 1.2 — — 
Prime St LLC, ABF Equity— — — — — — — — — — 
Prime St LLC, Structured Mezzanine27.6 — — — 0.3 27.9 1.1 0.9 — — 
Roemanu LLC, ABF Equity238.9 — — — (2.9)236.0 — — — 2.2 
TDC LLP, Preferred Equity36.8 3.6 (41.9)1.0 0.5 — 0.8 — — — 
TDC LLP, ABF Equity1.9 — (2.0)— 0.1 — — — — — 
Portfolio Company
Fair Value at December 31, 2024
Gross Additions(1)
Gross Reductions(2)
Net Realized Gain (Loss)Net Change in Unrealized Appreciation (Depreciation)
Fair Value at March 31, 2025
Interest Income(3)
PIK Income(3)
Fee Income(3)
Dividend and Other Income(3)
Credit Opportunities Partners JV, LLC
Credit Opportunities Partners JV, LLC$1,363.3 $297.7 $— $— $— $1,661.0 $— $— $— $47.8 
Equity/Other
Accuride Corp, Common Stock— — — — — — — — — — 
Accuride Corp, Preferred Stock— — — — — — — — — — 
Alacrity Solutions Group LLC, Common Stock— 1.9 — — (0.1)1.8 — — — — 
Alacrity Solutions Group LLC, Preferred Equity— 2.3 — — — 2.3 — — — — 
ATX Networks Corp, Common Stock— — — — — — — — — — 
ATX Networks Corp, Class B-1 Common Stock— — — — — — — — — — 
ATX Networks Corp, Class B-2 Common Stock— — — — — — — — — — 
Borden (New Dairy Opco), Common Stock18.4 — — — 0.1 18.5 — — — — 
Gracent LLC, Preferred Stock B— — — — — — — — — — 
Gracent LLC, Class A Common Stock— — — — — — — — — — 
Gracent LLC, Preferred Equity5.0 — — — (1.0)4.0 — — — — 
HM Dunn Co Inc, Preferred Stock, Series A0.1 — — — 0.1 0.2 — — — — 
HM Dunn Co Inc, Preferred Stock, Series B— — — — — — — — — — 
JW Aluminum Co, Common Stock2.5 — — — — 2.5 — — — — 
JW Aluminum Co, Preferred Stock152.3 — (21.1)— (0.5)130.7 — — — — 
Kellermeyer Bergensons Services LLC, Common Stock— — — — — — — — — — 
Kellermeyer Bergensons Services LLC, Preferred Stock15.1 — — — 4.1 19.2 — — — — 
NCI Inc, Class A-1 Common Stock— — — — — — — — — — 
NCI Inc, Class B-1 Common Stock— — — — — — — — — — 
NCI Inc, Class C Common Stock33.1 — — — 3.3 36.4 — — — — 
NCI Inc, Class I-1 Common Stock— — — — — — — — — — 
PRG III LLC, Preferred Stock, Series A PIK67.2 — — — (44.9)22.3 — — — — 
PRG III LLC, Preferred Stock, Series B PIK— — — — — — — — — — 
Quoizel, LLC, Common Stock6.1 — — — 0.2 6.3 — — — — 
Quorum Health Corp, Trade Claim0.9 — — — — 0.9 — — — — 
Quorum Health Corp, Trust Initial Funding Units0.1 — — — — 0.1 — — — — 
Quorum Health Corp, Private Equity10.1 0.9 — — (0.3)10.7 — — — — 
Wittur Holding GmbH, Common Stock10.9 — — — 3.2 14.1 — — — — 
Worldwise Inc, Common Stock0.7 — — — (0.5)0.2 — — — — 
Total$3,776.7 $363.4 $(271.8)$12.5 $(51.5)$3,829.3 $15.4 $28.0 $— $59.8 
[35] The investment, or a portion of the investment is not a qualifying asset under the Investment Company Act of 1940, as amended. A business development company may not acquire any asset other than qualifying assets, unless, at the time the acquisition is made, qualifying assets represent at least 70% of the company’s total assets. As of March 31, 2025, 70.8% of the Company’s total assets represented qualifying assets.
[36] Security or portion thereof held within Juniata River LLC and is pledged as collateral supporting the amounts outstanding under a term loan credit facility with JPMorgan Chase Bank, N.A. (see Note 9).
[37] Security or portion thereof held within Juniata River LLC and is pledged as collateral supporting the amounts outstanding under a term loan credit facility with JPMorgan Chase Bank, N.A.
[38] Asset is on non-accrual status.
[39] Asset is on non-accrual status.
[40] Position or portion thereof unsettled as of unsettled as of December 31, 2024.
[41] Security or portion thereof held within FS KKR MM CLO 1 LLC (see Note 9).
[42] Security or portion thereof held within KKR - FSK CLO 2 LLC (see Note 9).
[43] Security or portion thereof held within Meadowbrook Run LLC and is pledged as collateral supporting the amounts outstanding under a revolving credit facility with Morgan Stanley Senior Funding, Inc. (see Note 9).
[44] Security or portion thereof held within FS KKR MM CLO 1 LLC (see Note 9)
[45] Security is classified as Level 1 or Level 2 in the Company’s fair value hierarchy (see Note 8).
[46] Security is classified as Level 1 or Level 2 in the Company’s fair value hierarchy (see Note 8).
[47] Security or portion thereof held within Ambler Funding LLC and is pledged as collateral supporting the amounts outstanding under the revolving credit facility with Ally Bank (see Note 9).
[48] Security held within FSIC II Investments, Inc., a wholly-owned subsidiary of the Company.
[49] Security held within IC American Energy Investments, Inc., a wholly-owned subsidiary of the Company.
[50] Security held within FSIC II Investments, Inc., a wholly-owned subsidiary of the Company.
[51] Security held within IC American Energy Investments, Inc., a wholly-owned subsidiary of the Company.
[52] Security held within CCT Holdings II LLC, a wholly-owned subsidiary of the Company.
[53] Security held within CCT Holdings II LLC, a wholly-owned subsidiary of the Company.
[54] Security or portion thereof held within Race Street Funding LLC. Security is available as collateral supporting the amounts outstanding under the Senior Secured Revolving Credit Facility (see Note 9).
[55] Security or portion thereof held within Race Street Funding LLC. Security is available as collateral to support the amounts outstanding under the Senior Secured Revolving Credit Facility (see Note 9).
[56] Security held within FSIC Investments, Inc., a wholly-owned subsidiary of the Company.
[57] Security or portion thereof held within Cobbs Creek LLC and is pledged as collateral supporting the amounts outstanding under the senior secured revolving credit facility.
[58] Security or portion thereof held within Cobbs Creek LLC and is pledged as collateral supporting the amounts outstanding under the senior secured revolving credit facility.
[59] Position or portion thereof unsettled as of March 31, 2025.
[60] Security held within FSIC Investments, Inc., a wholly-owned subsidiary of the Company.
[61] Security held within IC Northern Investments, LLC, a wholly-owned subsidiary of the Company.
[62] Security held within IC Northern Investments, LLC, a wholly-owned subsidiary of the Company.