v3.26.1
Schedules of Investments and Advances to Affiliates (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [1],[2],[3] $ 4,071,008,000    
Fair value, ending balance 4,050,457,000 [4],[5],[6]   $ 4,071,008,000 [1],[2],[3]
Net change in deferred taxes 2,958,000 $ (2,047,000) (6,100,000)
Total Control Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 17,491,000   76,091,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 686,505,000 785,556,000 785,556,000
Gross additions 29,460,000   142,549,000
Gross reductions (12,098,000)   (222,647,000)
Realized Gain/(Loss) (33,020,000)   (134,000)
Change in Unrealized Gain (Loss) 37,963,000   (18,819,000)
Fair value, ending balance 708,810,000   686,505,000
Total Affiliate Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 626,000   2,996,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 49,827,000 35,596,000 35,596,000
Gross additions 430,000   30,865,000
Gross reductions (16,650,000)   (8,345,000)
Realized Gain/(Loss) (447,000)   15,000
Change in Unrealized Gain (Loss) (434,000)   (8,304,000)
Fair value, ending balance 32,726,000   49,827,000
Total Control & Affiliate Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 18,117,000   79,087,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 736,332,000 821,152,000 821,152,000
Gross additions 29,890,000   173,414,000
Gross reductions (28,748,000)   (230,992,000)
Realized Gain/(Loss) (33,467,000)   (119,000)
Change in Unrealized Gain (Loss) 37,529,000   (27,123,000)
Fair value, ending balance 741,536,000   736,332,000
Investment, Affiliated Issuer, No Longer Held      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 7,900   117,100
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Realized Gain/(Loss) (33,500,000)   15,200
Change in Unrealized Gain (Loss) 34,000,000.0   (20,100)
Investment, Identifier [Axis]: Urban One, Inc. | Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7] 490,000    
Fair value, ending balance [7]     490,000
Investment, Identifier [Axis]: 1236904 BC, Ltd. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 3,511,000    
Fair value, ending balance 581,000 [10],[11]   3,511,000 [8],[9]
Investment, Identifier [Axis]: 1236904 BC, Ltd. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 4,588,000    
Fair value, ending balance 4,489,000 [10],[11],[13]   4,588,000 [8],[9],[12]
Investment, Identifier [Axis]: AAdvantage Loyalty IP, Ltd., Passenger Airlines      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,997,000    
Fair value, ending balance 3,937,000   3,997,000
Investment, Identifier [Axis]: ACE Solutions, LLC | Oil, Gas & Consumable Fuels 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] (47,000)    
Investment, Identifier [Axis]: ACE Solutions, LLC | Oil, Gas & Consumable Fuels 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (113,000)    
Investment, Identifier [Axis]: ACE Solutions, LLC | Oil, Gas & Consumable Fuels 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 10,392,000    
Investment, Identifier [Axis]: ADCS Clinics Intermediate Holdings, LLC | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 123,000    
Fair value, ending balance 119,000 [11]   123,000 [9]
Investment, Identifier [Axis]: ADCS Clinics Intermediate Holdings, LLC | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 243,000    
Fair value, ending balance 650,000 [11],[14]   243,000 [9],[15]
Investment, Identifier [Axis]: ADCS Clinics Intermediate Holdings, LLC | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 3,825,000    
Fair value, ending balance 3,697,000 [10],[11]   3,825,000 [8],[9]
Investment, Identifier [Axis]: ADCS Clinics Intermediate Holdings, LLC | Health Care Providers & Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 18,658,000    
Fair value, ending balance 18,030,000 [10],[11]   18,658,000 [8],[9]
Investment, Identifier [Axis]: ADMI Corp., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,669,000    
Fair value, ending balance 2,657,000   2,669,000
Investment, Identifier [Axis]: AIG CLO, Ltd. 21-1A F, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,320,000    
Fair value, ending balance 1,320,000   1,320,000
Investment, Identifier [Axis]: ARC Falcon I, Inc., Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,955,000    
Fair value, ending balance 4,900,000   4,955,000
Investment, Identifier [Axis]: Accel International Holdings, LLC | Electrical Equipment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (21,000)    
Fair value, ending balance 0 [11],[14]   (21,000) [9],[15]
Investment, Identifier [Axis]: Accel International Holdings, LLC | Electrical Equipment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 27,560,000    
Fair value, ending balance 27,685,000 [10],[11],[13]   27,560,000 [8],[9],[12]
Investment, Identifier [Axis]: Acrisure, LLC, Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,154,000    
Fair value, ending balance 4,976,000   5,154,000
Investment, Identifier [Axis]: Adelaide Borrower, LLC | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Adelaide Borrower, LLC | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 898,000    
Fair value, ending balance 599,000 [11],[14]   898,000 [9],[15]
Investment, Identifier [Axis]: Adelaide Borrower, LLC | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 35,895,000    
Fair value, ending balance 35,895,000 [10],[11],[13]   35,895,000 [8],[9],[12]
Investment, Identifier [Axis]: Adtalem Global Education, Inc., Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 238,000    
Fair value, ending balance     238,000
Investment, Identifier [Axis]: Alera Group, Inc. | Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[12] 22,528,000    
Fair value, ending balance 21,377,000 [10],[13]   22,528,000 [8],[12]
Investment, Identifier [Axis]: Alera Group, Inc., Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,794,000    
Fair value, ending balance 7,497,000   7,794,000
Investment, Identifier [Axis]: Allwyn Entertainment Financing US, LLC, Hotels, Restaurants & Leisure      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,860,000    
Fair value, ending balance 6,860,000   6,860,000
Investment, Identifier [Axis]: American Auto Auction Group, LLC, Commercial Services & Supplies      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 1,979,000    
Investment, Identifier [Axis]: American Rock Salt Company, LLC | Chemicals 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8] 1,516,000    
Fair value, ending balance 1,775,000 [10]   1,516,000 [8]
Investment, Identifier [Axis]: American Rock Salt Company, LLC | Chemicals 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 4,855,000    
Fair value, ending balance 5,276,000 [10],[11]   4,855,000 [8],[9]
Investment, Identifier [Axis]: American Rock Salt Company, LLC, Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,570,000    
Fair value, ending balance     1,570,000
Investment, Identifier [Axis]: American Rock Salt Company, LLC, Chemicals, S+ 7.25% (11.03%)      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 1,706,000    
Investment, Identifier [Axis]: Amylu Borrower Sub, LLC | Food Products 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 1,138,000 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Amylu Borrower Sub, LLC | Food Products 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Amylu Borrower Sub, LLC | Food Products 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 39,436,000    
Fair value, ending balance 39,336,000 [10],[11]   39,436,000 [8],[9]
Investment, Identifier [Axis]: Aprio Advisory Group, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (112,000)    
Fair value, ending balance (107,000) [11],[14]   (112,000) [9],[15]
Investment, Identifier [Axis]: Aprio Advisory Group, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (9,000)    
Fair value, ending balance 295,000 [11],[14]   (9,000) [9],[15]
Investment, Identifier [Axis]: Arch Global Precision, LLC | Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 938,000    
Fair value, ending balance 2,197,000 [11]   938,000 [9],[15]
Investment, Identifier [Axis]: Arch Global Precision, LLC | Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 2,241,000    
Fair value, ending balance 801,000 [11],[14]   2,241,000 [9]
Investment, Identifier [Axis]: Arch Global Precision, LLC | Machinery 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 7,112,000    
Fair value, ending balance 6,972,000 [10],[11],[13]   7,112,000 [8],[9],[12]
Investment, Identifier [Axis]: Arches Buyer, Inc., Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,923,000    
Fair value, ending balance 5,870,000   5,923,000
Investment, Identifier [Axis]: Arcline FM Holdings, LLC, Aerospace & Defense      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,989,000    
Fair value, ending balance 4,964,000   4,989,000
Investment, Identifier [Axis]: Arctic Holdco, LLC | Trading Companies & Distributors 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 3,243,000    
Fair value, ending balance 3,235,000 [11],[14]   3,243,000 [9],[15]
Investment, Identifier [Axis]: Arctic Holdco, LLC | Trading Companies & Distributors 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 632,000    
Fair value, ending balance 1,159,000 [11],[14]   632,000 [9],[15]
Investment, Identifier [Axis]: Arctic Holdco, LLC | Trading Companies & Distributors 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 45,922,000    
Fair value, ending balance 45,806,000 [10],[11],[13]   45,922,000 [8],[9],[12]
Investment, Identifier [Axis]: Armada Parent, Inc. | Aerospace & Defense 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 3,841,000    
Fair value, ending balance 3,831,000 [11]   3,841,000 [9]
Investment, Identifier [Axis]: Armada Parent, Inc. | Aerospace & Defense 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Armada Parent, Inc. | Aerospace & Defense 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 55,492,000    
Fair value, ending balance 55,353,000 [10],[11]   55,492,000 [8],[9]
Investment, Identifier [Axis]: Artera Services, LLC, Construction & Engineering      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,440,000    
Fair value, ending balance 4,680,000   4,440,000
Investment, Identifier [Axis]: Artifact Bidco, Inc | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Artifact Bidco, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Artifact Bidco, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Artifact Bidco, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 10,875,000    
Fair value, ending balance 10,875,000 [10],[11],[13]   10,875,000 [8],[9],[12]
Investment, Identifier [Axis]: Ascend Learning, LLC , Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,984,000    
Fair value, ending balance 3,866,000   3,984,000
Investment, Identifier [Axis]: Ascensus Group Holdings, Inc. | Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 16,600,000    
Fair value, ending balance 16,850,000   16,600,000 [9]
Investment, Identifier [Axis]: Ascensus Group Holdings, Inc., Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,472,000    
Fair value, ending balance 7,356,000   7,472,000
Investment, Identifier [Axis]: Athenahealth Group, Inc., Health Care Technology      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,935,000    
Fair value, ending balance 7,747,000   9,935,000
Investment, Identifier [Axis]: Athletico Management, LLC, Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,577,000    
Fair value, ending balance     3,577,000
Investment, Identifier [Axis]: AuditBoard, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 10,898,000    
Fair value, ending balance 10,735,000 [11]   10,898,000 [9]
Investment, Identifier [Axis]: AuditBoard, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [15] 0    
Fair value, ending balance (65,000) [11],[14]   0 [15]
Investment, Identifier [Axis]: AuditBoard, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 22,887,000    
Fair value, ending balance 22,544,000 [10],[11],[13]   22,887,000 [8],[9]
Investment, Identifier [Axis]: AuditBoard, Inc. | Software 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 5,742,000    
Fair value, ending balance 5,655,000 [10],[11],[13]   5,742,000 [8],[9]
Investment, Identifier [Axis]: Avalara, Inc, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,992,000    
Fair value, ending balance     5,992,000
Investment, Identifier [Axis]: Aventine Holdings, LLC | Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 41,466,000    
Fair value, ending balance 38,945,000 [11]   41,466,000 [8],[9]
Investment, Identifier [Axis]: Aventine Holdings, LLC | Entertainment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 9,809,000    
Fair value, ending balance 9,895,000 [11]   9,809,000 [8],[9]
Investment, Identifier [Axis]: Aventine Holdings, LLC | Entertainment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 24,777,000    
Fair value, ending balance 24,314,000 [11],[13]   24,777,000 [8],[9],[12]
Investment, Identifier [Axis]: Axiom Global, Inc. | Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 46,659,000    
Fair value, ending balance 46,541,000 [10],[11],[13]   46,659,000 [8],[9],[12]
Investment, Identifier [Axis]: Azurite Intermediate Holdings, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (91,000)    
Investment, Identifier [Axis]: Azurite Intermediate Holdings, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 22,639,000    
Fair value, ending balance 22,073,000 [11]   22,639,000 [9]
Investment, Identifier [Axis]: Azurite Intermediate Holdings, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 9,712,000 [11]   0 [9],[15]
Investment, Identifier [Axis]: Azurite Intermediate Holdings, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 9,961,000    
Fair value, ending balance [9]     9,961,000
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc. | Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[12],[16],[17] 12,528,000    
Fair value, ending balance 12,529,000 [11],[18],[19],[20]   12,528,000 [7],[9],[12],[16],[17]
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[17] 0    
Fair value, ending balance 3,349,000 [11],[20]   0 [9],[15],[17]
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17] 4,984,000    
Fair value, ending balance 5,198,000 [11],[20]   4,984,000 [9],[17]
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc. | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17] 8,307,000    
Fair value, ending balance 8,664,000 [11],[20]   8,307,000 [9],[17]
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc., Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 12,528,000 0 0
Gross additions 0   12,528,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 1,000   0
Fair value, ending balance 12,529,000   12,528,000
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc., Senior Secured First Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc., Senior Secured First Lien Debt 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 36,000   12,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions 3,353,000   169,000
Gross reductions (83,000)   (246,000)
Realized Gain/(Loss) 0   (86,000)
Change in Unrealized Gain (Loss) 79,000   163,000
Fair value, ending balance 3,349,000   0
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc., Senior Secured First Lien Debt 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 214,000   146,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 8,307,000 0 0
Gross additions 357,000   8,307,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 8,664,000   8,307,000
Investment, Identifier [Axis]: BCPE Oceandrive Buyer, Inc., Senior Secured First Lien Debt 3      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 61,000   235,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,984,000 0 0
Gross additions 214,000   10,109,000
Gross reductions 0   (5,373,000)
Realized Gain/(Loss) 0   248,000
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 5,198,000   4,984,000
Investment, Identifier [Axis]: Battalion CLO, Ltd. 21-17A F, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 570,000    
Fair value, ending balance 281,000   570,000
Investment, Identifier [Axis]: Bayou Holdings Buyer, Inc. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (29,000)    
Fair value, ending balance (28,000) [11],[14]   (29,000) [9],[15]
Investment, Identifier [Axis]: Bayou Holdings Buyer, Inc. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (31,000)    
Fair value, ending balance (30,000) [11],[14]   (31,000) [9],[15]
Investment, Identifier [Axis]: Bayou Holdings Buyer, Inc. | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 21,200,000    
Fair value, ending balance 21,151,000 [10],[11]   21,200,000 [8],[9]
Investment, Identifier [Axis]: Beach Acquisition Bidco, LLC, Textiles, Apparel & luxury goods      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,460,000    
Fair value, ending balance 1,448,000   1,460,000
Investment, Identifier [Axis]: Bella Holding Co., LLC , Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 7,982,000    
Investment, Identifier [Axis]: Bella Holding Co., LLC, Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 8,047,000    
Fair value, ending balance     8,047,000
Investment, Identifier [Axis]: Belron Finance 2019, LLC, Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,756,000    
Fair value, ending balance 5,708,000   5,756,000
Investment, Identifier [Axis]: Big Apple Advisory, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 5,209,000    
Fair value, ending balance 6,108,000 [11],[14]   5,209,000 [9],[15]
Investment, Identifier [Axis]: Big Apple Advisory, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Big Apple Advisory, LLC | Financial Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 47,166,000    
Fair value, ending balance 47,047,000 [10],[11],[13]   47,166,000 [8],[9],[12]
Investment, Identifier [Axis]: Bingo Group Buyer, Inc. | Commercial Services & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 1,547,000 [11]   0 [9],[15]
Investment, Identifier [Axis]: Bingo Group Buyer, Inc. | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,551,000    
Fair value, ending balance 1,687,000 [11]   1,551,000 [9]
Investment, Identifier [Axis]: Bingo Group Buyer, Inc. | Commercial Services & Supplies 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,691,000    
Fair value, ending balance 0 [11],[14]   1,691,000 [9]
Investment, Identifier [Axis]: Bingo Group Buyer, Inc. | Commercial Services & Supplies 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 20,000    
Fair value, ending balance 20,000 [11],[14]   20,000 [9],[15]
Investment, Identifier [Axis]: Bingo Group Buyer, Inc. | Commercial Services & Supplies 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 5,410,000    
Fair value, ending balance 5,396,000 [10],[11],[13]   5,410,000 [8],[9],[12]
Investment, Identifier [Axis]: Black Mountain Sand, LLC | Energy Equipment & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 1,304,000    
Fair value, ending balance 1,304,000 [11],[19],[22]   1,304,000 [7],[9],[16],[21]
Investment, Identifier [Axis]: Blackhawk Network Holdings, Inc., Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,944,000    
Fair value, ending balance 4,843,000   4,944,000
Investment, Identifier [Axis]: Blackstone CQP Holdco, LP, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,929,000    
Fair value, ending balance     4,929,000
Investment, Identifier [Axis]: CCI Buyer, Inc. | Wireless Telecommunication Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: CCI Buyer, Inc. | Wireless Telecommunication Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 52,129,000    
Fair value, ending balance 51,998,000 [10],[11],[13]   52,129,000 [8],[9],[12]
Investment, Identifier [Axis]: CD&R Hydra Buyer, Inc., Industrial Conglomerates      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,182,000    
Fair value, ending balance 8,160,000   6,182,000
Investment, Identifier [Axis]: CNT Holdings I Corp., Personal Care Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,043,000    
Fair value, ending balance 6,009,000   6,043,000
Investment, Identifier [Axis]: CQP Holdco, LP, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,888,000    
Investment, Identifier [Axis]: CRS-SPV, Inc. | Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[23] 2,008,000    
Fair value, ending balance 2,008,000 [11],[18],[19],[24]   2,008,000 [7],[9],[16],[23]
Investment, Identifier [Axis]: CRS-SPV, Inc., Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,008,000 1,704,000 1,704,000
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   304,000
Fair value, ending balance 2,008,000   2,008,000
Investment, Identifier [Axis]: Capstone Acquisition Holdings, Inc. | Air Freight & Logistics 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 208,000    
Fair value, ending balance 207,000 [11]   208,000 [9]
Investment, Identifier [Axis]: Capstone Acquisition Holdings, Inc. | Air Freight & Logistics 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 20,550,000    
Fair value, ending balance 20,498,000 [10],[11]   20,550,000 [8],[9]
Investment, Identifier [Axis]: Carlyle GMS CLO, 16-3A FRR, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,823,000    
Fair value, ending balance 1,823,000   1,823,000
Investment, Identifier [Axis]: Carr, Riggs & Ingram Capital, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 1,592,000    
Fair value, ending balance 1,922,000 [11],[14]   1,592,000 [9],[15]
Investment, Identifier [Axis]: Carr, Riggs & Ingram Capital, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 1,798,000 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Carr, Riggs & Ingram Capital, LLC | Financial Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 11,620,000    
Fair value, ending balance 11,591,000 [10],[11],[13]   11,620,000 [8],[9],[12]
Investment, Identifier [Axis]: Center Phase Energy, LLC | Electric Utilities 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 10,305,000    
Fair value, ending balance 10,305,000 [10],[11]   10,305,000 [8],[9]
Investment, Identifier [Axis]: Center Phase Energy, LLC | Electric Utilities 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 15,186,000    
Fair value, ending balance 15,147,000 [10],[11]   15,186,000 [8],[9]
Investment, Identifier [Axis]: Center Phase Energy, LLC | Electric Utilities 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[21] 2,386,000    
Fair value, ending balance 2,386,000 [11],[19],[22]   2,386,000 [7],[9],[21]
Investment, Identifier [Axis]: Center Phase Energy, LLC | Electric Utilities 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[21] 636,000    
Fair value, ending balance 636,000 [11],[19],[22]   636,000 [7],[9],[21]
Investment, Identifier [Axis]: Charter Industries Holdings, LLC | Distributors 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (34,000)    
Fair value, ending balance (33,000) [11],[14]   (34,000) [9],[15]
Investment, Identifier [Axis]: Charter Industries Holdings, LLC | Distributors 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (51,000)    
Fair value, ending balance (49,000) [11],[14]   (51,000) [9],[15]
Investment, Identifier [Axis]: Charter Industries Holdings, LLC | Distributors 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 29,807,000    
Fair value, ending balance 28,983,000 [10],[11]   29,807,000 [8],[9]
Investment, Identifier [Axis]: Cirque Du Soleil Holding USA Newco, Inc. | Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [18],[19],[25] 16,611,000    
Investment, Identifier [Axis]: Cirque Du Soleil Holding USA Newco, Inc. | Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[16],[23],[26] 14,632,000    
Fair value, ending balance [7],[16],[23],[26]     14,632,000
Investment, Identifier [Axis]: Cirque Du Soleil Holding USA Newco, Inc., Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,756,000    
Fair value, ending balance 6,894,000   6,756,000
Investment, Identifier [Axis]: Cirque Du Soleil Holding USA Newco, Inc., Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 14,632,000 0 0
Gross additions 0   17,441,000
Gross reductions (14,632,000)   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   (2,809,000)
Fair value, ending balance 0   14,632,000
Investment, Identifier [Axis]: Citadel Securities, LP, Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,432,000    
Fair value, ending balance 4,402,000   4,432,000
Investment, Identifier [Axis]: Clarios Global, LP, Automobile Components      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 10,012,000    
Fair value, ending balance 9,915,000   10,012,000
Investment, Identifier [Axis]: Cliffwater, LLC | Capital Markets 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Cliffwater, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 30,078,000    
Investment, Identifier [Axis]: Cliffwater, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Cliffwater, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 30,154,000    
Fair value, ending balance [8],[9],[12]     30,154,000
Investment, Identifier [Axis]: Clover Holding 2, LLC, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,219,000    
Fair value, ending balance 4,983,000   5,219,000
Investment, Identifier [Axis]: Coalesce Merlin Purchaser, LLC | Commercial Services & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 715,000    
Fair value, ending balance 3,450,000 [11],[14]   715,000 [9],[15]
Investment, Identifier [Axis]: Coalesce Merlin Purchaser, LLC | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (32,000)    
Fair value, ending balance (32,000) [11],[14]   (32,000) [9],[15]
Investment, Identifier [Axis]: Coalesce Merlin Purchaser, LLC | Commercial Services & Supplies 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 17,300,000    
Fair value, ending balance 17,256,000 [10],[11],[13]   17,300,000 [8],[9],[12]
Investment, Identifier [Axis]: Cold Spring Brewing, Co. | Beverages      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 20,556,000    
Fair value, ending balance 20,556,000 [10],[11],[13]   20,556,000 [8],[9],[12]
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 24,607,000    
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 1,188,000    
Fair value, ending balance 1,412,000 [11],[14]   1,188,000 [9],[15]
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 24,672,000    
Fair value, ending balance [8],[9]     24,672,000
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 24,357,000    
Fair value, ending balance 24,295,000 [10],[11]   24,357,000 [8],[9]
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 2,420,000    
Fair value, ending balance 2,414,000 [10],[11]   2,420,000 [8],[9]
Investment, Identifier [Axis]: Communication Technology Intermediate, LLC | Professional Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 8,582,000    
Fair value, ending balance 8,560,000 [10],[11],[13]   8,582,000 [8],[9],[12]
Investment, Identifier [Axis]: Compass Power Generation, LLC, Independent Power and Renewable Electricity Producers      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,467,000    
Fair value, ending balance 6,228,000   6,467,000
Investment, Identifier [Axis]: Connectwise, LL, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 5,173,000    
Investment, Identifier [Axis]: Connectwise, LLC, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 10,427,000    
Fair value, ending balance     10,427,000
Investment, Identifier [Axis]: Conservice Midco, LLC, Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,423,000    
Fair value, ending balance     5,423,000
Investment, Identifier [Axis]: Consolidated Precision Products Corp. | Aerospace & Defense      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[21] 21,867,000    
Fair value, ending balance 20,812,000 [11],[22]   21,867,000 [9],[21]
Investment, Identifier [Axis]: Corelogic, Inc. | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10] 8,617,000    
Investment, Identifier [Axis]: Corelogic, Inc. | IT Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8] 9,326,000    
Fair value, ending balance [8]     9,326,000
Investment, Identifier [Axis]: Corelogic, Inc., Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 8,455,000    
Investment, Identifier [Axis]: Corelogic, Inc., IT Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 8,879,000    
Fair value, ending balance     8,879,000
Investment, Identifier [Axis]: Corfin Industries, LLC | Aerospace & Defense 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 1,545,000    
Investment, Identifier [Axis]: Corfin Industries, LLC | Aerospace & Defense 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 9,411,000    
Investment, Identifier [Axis]: Corfin Industries, LLC | Aerospace & Defense 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 15,807,000    
Investment, Identifier [Axis]: Corfin Industries, LLC | Aerospace & Defense 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 19,533,000    
Investment, Identifier [Axis]: Corfin Industries, LLC | Electrical Equipment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,549,000    
Fair value, ending balance [9]     1,549,000
Investment, Identifier [Axis]: Corfin Industries, LLC | Electrical Equipment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 9,435,000    
Fair value, ending balance [9]     9,435,000
Investment, Identifier [Axis]: Corfin Industries, LLC | Electrical Equipment 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 15,849,000    
Fair value, ending balance [8],[9],[12]     15,849,000
Investment, Identifier [Axis]: Corfin Industries, LLC | Electrical Equipment 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 19,582,000    
Fair value, ending balance [8],[9],[12]     19,582,000
Investment, Identifier [Axis]: Cornerstone Building Brands, Inc., Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,798,000    
Fair value, ending balance     2,798,000
Investment, Identifier [Axis]: Cornerstone Chemical, Co. | Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19] 3,107,000    
Investment, Identifier [Axis]: Cornerstone Chemical, Co. | Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 3,107,000    
Fair value, ending balance [7],[9],[16]     3,107,000
Investment, Identifier [Axis]: Coronis Health I, LLC | Health Care Technology 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[23] 532,000    
Fair value, ending balance 798,000 [11],[14],[24]   532,000 [9],[15],[23]
Investment, Identifier [Axis]: Coronis Health I, LLC | Health Care Technology 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23] 4,225,000    
Fair value, ending balance 4,342,000 [11],[24]   4,225,000 [9],[23]
Investment, Identifier [Axis]: Coronis Health I, LLC | Health Care Technology 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23] 2,751,000    
Fair value, ending balance 2,785,000 [11],[24]   2,751,000 [9],[23]
Investment, Identifier [Axis]: Coronis Health I, LLC | Health Care Technology 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[23] 4,900,000    
Fair value, ending balance 4,900,000 [11],[18],[19],[24]   4,900,000 [7],[9],[16],[23]
Investment, Identifier [Axis]: Coronis Health I, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,900,000 0 0
Gross additions 0   4,900,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 4,900,000   4,900,000
Investment, Identifier [Axis]: Coronis Health I, LLC, Senior Secured First Lien Debt 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 14,000   37,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 532,000 0 0
Gross additions 266,000   532,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 798,000   532,000
Investment, Identifier [Axis]: Coronis Health I, LLC, Senior Secured First Lien Debt 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 115,000   311,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,225,000 0 0
Gross additions 117,000   4,225,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 4,342,000   4,225,000
Investment, Identifier [Axis]: Coronis Health I, LLC, Senior Secured Second Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 34,000   92,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,751,000 0 0
Gross additions 34,000   2,751,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 2,785,000   2,751,000
Investment, Identifier [Axis]: Cotiviti, Inc., Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,528,000    
Fair value, ending balance 4,330,000   4,528,000
Investment, Identifier [Axis]: Cotiviti, Inc., Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,424,000    
Fair value, ending balance 9,011,000   9,424,000
Investment, Identifier [Axis]: Crisis Prevention Institute, Inc., Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,290,000    
Fair value, ending balance 2,275,000   2,290,000
Investment, Identifier [Axis]: Crown Finance US, Inc., Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,873,000    
Fair value, ending balance 4,881,000   4,873,000
Investment, Identifier [Axis]: Danish CRJ, Ltd. (2) (4), Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Demakes Borrower, LLC | Consumer Staples Distribution & Retail      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 17,577,000    
Fair value, ending balance 17,532,000 [10],[11]   17,577,000 [8],[9]
Investment, Identifier [Axis]: Directv Financing, LLC, Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 196,000    
Fair value, ending balance     196,000
Investment, Identifier [Axis]: EIG Management Co., LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,442,000    
Fair value, ending balance 3,442,000   3,442,000
Investment, Identifier [Axis]: EMRLD Borrower, LP, Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 1,863,000    
Investment, Identifier [Axis]: Eaton Vance CDO, Ltd. 15-1A FR, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 846,000    
Fair value, ending balance 381,000   846,000
Investment, Identifier [Axis]: Edelman Financial Center, LLC | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8] 9,468,000    
Fair value, ending balance 9,391,000 [10]   9,468,000 [8]
Investment, Identifier [Axis]: Edelman Financial Center, LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,734,000    
Fair value, ending balance     4,734,000
Investment, Identifier [Axis]: Edelman Financial Center, LLC, Capital Markets, S+ 5.25% (8.92%)      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,695,000    
Investment, Identifier [Axis]: Einstein Parent, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (12,000)    
Fair value, ending balance (69,000) [11],[14]   (12,000) [9],[15]
Investment, Identifier [Axis]: Einstein Parent, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 22,206,000    
Fair value, ending balance 21,648,000 [10],[11],[13]   22,206,000 [8],[9],[12]
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Construction & Engineering 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 6,379,000    
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Construction & Engineering 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 2,127,000    
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Construction & Engineering 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 27,909,000    
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Electric Power Engineers, LLC | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 27,909,000    
Fair value, ending balance [8],[9],[12]     27,909,000
Investment, Identifier [Axis]: Electro-Methods, LP | Aerospace & Defense 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Electro-Methods, LP | Aerospace & Defense 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 34,326,000    
Investment, Identifier [Axis]: Electro-Methods, LP | Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Electro-Methods, LP | Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 34,412,000    
Fair value, ending balance [8],[9],[12]     34,412,000
Investment, Identifier [Axis]: Eliassen Group, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 1,344,000    
Fair value, ending balance 1,340,000 [10],[11]   1,344,000 [8],[9]
Investment, Identifier [Axis]: Eliassen Group, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 16,802,000    
Fair value, ending balance 16,759,000 [10],[11],[13]   16,802,000 [8],[9],[12]
Investment, Identifier [Axis]: Emerald Borrower, LP, Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,297,000    
Fair value, ending balance 2,282,000   2,297,000
Investment, Identifier [Axis]: Ensemble RCM, LLC, Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 13,368,000    
Fair value, ending balance 12,835,000   13,368,000
Investment, Identifier [Axis]: Entain, PLC, Hotels, Restaurants & Leisure 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,747,000    
Fair value, ending balance 4,767,000   4,747,000
Investment, Identifier [Axis]: Entain, PLC, Hotels, Restaurants & Leisure 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,435,000    
Fair value, ending balance 3,446,000   3,435,000
Investment, Identifier [Axis]: Epicor Software Corp., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,086,000    
Fair value, ending balance 5,932,000   6,086,000
Investment, Identifier [Axis]: FBLC Senior Loan Fund, LLC | Investment in Joint Ventures      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[17],[27] 224,956,000    
Fair value, ending balance 222,706,000 [11],[19],[20],[28]   224,956,000 [7],[9],[17],[27]
Investment, Identifier [Axis]: FBLC Senior Loan Fund, LLC, Joint Venture      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 4,992,000   27,380,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 224,956,000 404,934,000 404,934,000
Gross additions 0   0
Gross reductions 0   (179,978,000)
Realized Gain/(Loss) 0   (296,000)
Change in Unrealized Gain (Loss) (2,250,000)   296,000
Fair value, ending balance 222,706,000   224,956,000
Investment, Identifier [Axis]: FGT Purchaser, LLC | Internet & Direct Marketing Retail 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (296,000)    
Investment, Identifier [Axis]: FGT Purchaser, LLC | Internet & Direct Marketing Retail 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 28,304,000    
Investment, Identifier [Axis]: FGT Purchaser, LLC | Specialty Retail 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (296,000)    
Fair value, ending balance [9],[15]     (296,000)
Investment, Identifier [Axis]: FGT Purchaser, LLC | Specialty Retail 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 28,164,000    
Fair value, ending balance [8],[9]     28,164,000
Investment, Identifier [Axis]: FNZ Group Entities, Ltd., Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,330,000    
Fair value, ending balance 2,330,000   2,330,000
Investment, Identifier [Axis]: Faraday Buyer, LLC | Electrical Equipment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 40,805,000    
Fair value, ending balance [8],[9]     40,805,000
Investment, Identifier [Axis]: Faraday Buyer, LLC | Electrical Equipment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 8,644,000    
Fair value, ending balance [8],[9]     8,644,000
Investment, Identifier [Axis]: FinThrive Software Intermediate Holdings, Inc., Health Care Technology      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,732,000    
Fair value, ending balance 2,419,000   2,732,000
Investment, Identifier [Axis]: First Eagle Greenway Fund II, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 255,000 255,000
Gross additions     0
Gross reductions     (244,000)
Realized Gain/(Loss)     (131,000)
Change in Unrealized Gain (Loss)     120,000
Fair value, ending balance     0
Investment, Identifier [Axis]: Fitness International, LLC, Hotels, Restaurants & Leisure      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,839,000    
Fair value, ending balance 6,824,000   6,839,000
Investment, Identifier [Axis]: FloWorks International, LLC | Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 4,958,000    
Fair value, ending balance [9]     4,958,000
Investment, Identifier [Axis]: FloWorks International, LLC | Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 39,366,000    
Fair value, ending balance [8],[9],[12]     39,366,000
Investment, Identifier [Axis]: FloWorks International, LLC | Trading Companies & Distributors 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 4,958,000    
Investment, Identifier [Axis]: FloWorks International, LLC | Trading Companies & Distributors 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 39,267,000    
Investment, Identifier [Axis]: Florida Food Products, LLC | Food Products 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8] 7,555,000    
Fair value, ending balance 7,321,000 [10]   7,555,000 [8]
Investment, Identifier [Axis]: Florida Food Products, LLC | Food Products 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 1,916,000    
Fair value, ending balance 1,975,000 [10],[11]   1,916,000 [8],[9]
Investment, Identifier [Axis]: Florida Food Products, LLC | Food Products 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8] 1,890,000    
Fair value, ending balance 1,877,000 [10]   1,890,000 [8]
Investment, Identifier [Axis]: Flow Traders Holding, LLC | Capital Markets 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[26] (91,000)    
Fair value, ending balance 16,357,000 [11],[25]   (91,000) [9],[15],[26]
Investment, Identifier [Axis]: Flow Traders Holding, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[26] 16,389,000    
Fair value, ending balance (88,000) [11],[14],[25]   16,389,000 [9],[26]
Investment, Identifier [Axis]: Focus Financial Partners, LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,443,000    
Fair value, ending balance 4,276,000   4,443,000
Investment, Identifier [Axis]: Foresight Energy Operating, LL, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 646,000    
Investment, Identifier [Axis]: Foresight Energy Operating, LLC | Oil, Gas & Consumable Fuels 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,037,000    
Fair value, ending balance 1,034,000 [11]   1,037,000 [9]
Investment, Identifier [Axis]: Foresight Energy Operating, LLC | Oil, Gas & Consumable Fuels 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 876,000    
Fair value, ending balance 876,000 [11],[18],[19],[22]   876,000 [7],[9],[16],[21]
Investment, Identifier [Axis]: Foresight Energy Operating, LLC, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 648,000    
Fair value, ending balance     648,000
Investment, Identifier [Axis]: Freeport LNG Investments, LLLP, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,820,000    
Fair value, ending balance 4,996,000   4,820,000
Investment, Identifier [Axis]: Gainwell Acquisition Corp., Health Care Technology      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 2,900,000    
Investment, Identifier [Axis]: Galaxy US OpCo, Inc., Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,229,000    
Fair value, ending balance     2,229,000
Investment, Identifier [Axis]: Galway Borrower, LLC | Insurance 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 920,000    
Fair value, ending balance 1,125,000 [11]   920,000 [9],[15]
Investment, Identifier [Axis]: Galway Borrower, LLC | Insurance 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 581,000    
Fair value, ending balance 1,264,000 [11],[14]   581,000 [9],[15]
Investment, Identifier [Axis]: Galway Borrower, LLC | Insurance 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 38,101,000    
Fair value, ending balance (17,000) [11],[14]   38,101,000 [8],[9]
Investment, Identifier [Axis]: Galway Borrower, LLC | Insurance 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 38,006,000    
Investment, Identifier [Axis]: Geon Performance Solutions, LLC, Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,555,000    
Fair value, ending balance 3,970,000   3,555,000
Investment, Identifier [Axis]: Geosyntec Consultants, Inc., Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,227,000    
Fair value, ending balance 9,118,000   9,227,000
Investment, Identifier [Axis]: Global Medical Response, Inc., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 10,022,000    
Fair value, ending balance 9,898,000   10,022,000
Investment, Identifier [Axis]: GoHealth, Inc. | Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [16],[21] 7,000    
Fair value, ending balance 5,000 [18],[22]   7,000 [16],[21]
Investment, Identifier [Axis]: Golden State Foods, LLC, Food Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,450,000    
Fair value, ending balance 6,419,000   6,450,000
Investment, Identifier [Axis]: Gordian Medical, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [10],[11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: Gordian Medical, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[8],[9] 2,944,000    
Fair value, ending balance 2,944,000 [10],[11],[18],[19]   2,944,000 [7],[8],[9]
Investment, Identifier [Axis]: Gordian Medical, Inc., Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,316,000    
Fair value, ending balance 7,316,000   7,316,000
Investment, Identifier [Axis]: Gordian Medical, Inc., Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0    
Fair value, ending balance 0   0
Investment, Identifier [Axis]: Greywolf CLO, Ltd. 20-3RA ER, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 916,000    
Fair value, ending balance 803,000   916,000
Investment, Identifier [Axis]: Groome Purchaser, LLC | Commercial Services & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (33,000)    
Fair value, ending balance (32,000) [11],[14]   (33,000) [9],[15]
Investment, Identifier [Axis]: Groome Purchaser, LLC | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (49,000)    
Fair value, ending balance (47,000) [11],[14]   (49,000) [9],[15]
Investment, Identifier [Axis]: Groome Purchaser, LLC | Commercial Services & Supplies 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (25,000)    
Fair value, ending balance (24,000) [11],[14]   (25,000) [9],[15]
Investment, Identifier [Axis]: Groome Purchaser, LLC | Commercial Services & Supplies 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 16,368,000    
Fair value, ending balance 16,333,000 [10],[11]   16,368,000 [8],[9]
Investment, Identifier [Axis]: Gulfside Supply, Inc., Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,375,000    
Fair value, ending balance 4,016,000   4,375,000
Investment, Identifier [Axis]: Hamilton Projects Acquiror, LLC, Independent Power and Renewable Electricity Producers      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,617,000    
Fair value, ending balance 6,442,000   6,617,000
Investment, Identifier [Axis]: HelpSystems Holdings, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,139,000    
Fair value, ending balance 5,647,000   4,139,000
Investment, Identifier [Axis]: Higginbotham Insurance Agency, Inc. | Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9] 10,046,000    
Fair value, ending balance 10,046,000 [11],[19]   10,046,000 [7],[9]
Investment, Identifier [Axis]: High Street Buyer, Inc. | Insurance      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 3,259,000    
Fair value, ending balance 5,023,000 [11],[14]   3,259,000 [9],[15]
Investment, Identifier [Axis]: Highbridge Loan Management, Ltd. 11A-17 E, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,592,000    
Fair value, ending balance 2,200,000   2,592,000
Investment, Identifier [Axis]: Hologic, Inc. | Health Care Equipment & Supplies      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 7,004,000    
Investment, Identifier [Axis]: Hologic, Inc., Health Care Equipment & Supplies      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 9,875,000    
Investment, Identifier [Axis]: Hometown Food, Co. | Food Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 14,973,000    
Fair value, ending balance 15,013,000 [10],[11],[13]   14,973,000 [8],[9],[12]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 4,615,000    
Fair value, ending balance 4,604,000 [11]   4,615,000 [9]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 2,085,000    
Fair value, ending balance 2,127,000 [11]   2,085,000 [9],[15]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 2,132,000    
Fair value, ending balance 2,680,000 [11],[14]   2,132,000 [9]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 24,828,000    
Fair value, ending balance 24,766,000 [10],[11]   24,828,000 [8],[9]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 6,444,000    
Fair value, ending balance 6,428,000 [10],[11]   6,444,000 [8],[9]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 6      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 8,401,000    
Fair value, ending balance 8,380,000 [10],[11]   8,401,000 [8],[9]
Investment, Identifier [Axis]: Hospice Care Buyer, Inc. | Health Care Providers & Services 7      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 3,528,000    
Fair value, ending balance 3,519,000 [10],[11]   3,528,000 [8],[9]
Investment, Identifier [Axis]: Hudson River Trading, LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,243,000    
Fair value, ending balance 5,184,000   5,243,000
Investment, Identifier [Axis]: Hunter Communications & Technologies, LLC | Diversified Telecommunication Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 409,000    
Investment, Identifier [Axis]: Hunter Communications | Diversified Telecommunication Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (6,000)    
Investment, Identifier [Axis]: Hunter Communications | Diversified Telecommunication Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 5,754,000    
Investment, Identifier [Axis]: Hunter Douglas, Inc., Household Durables      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,500,000    
Fair value, ending balance 4,446,000   4,500,000
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Air Freight & Logistics 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 4,052,000    
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Air Freight & Logistics 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (17,000)    
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Air Freight & Logistics 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 17,042,000    
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Ground Transportation 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 2,050,000    
Fair value, ending balance [9],[15]     2,050,000
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Ground Transportation 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (18,000)    
Fair value, ending balance [9],[15]     (18,000)
Investment, Identifier [Axis]: ICAT Intermediate Holdings, LLC | Ground Transportation 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 17,066,000    
Fair value, ending balance [8],[9]     17,066,000
Investment, Identifier [Axis]: ICR Operations, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 3,784,000    
Fair value, ending balance [9],[15]     3,784,000
Investment, Identifier [Axis]: ICR Operations, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 40,839,000    
Fair value, ending balance [8],[9]     40,839,000
Investment, Identifier [Axis]: ICR Operations, LLC | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 2,219,000    
Fair value, ending balance [8],[9]     2,219,000
Investment, Identifier [Axis]: IDERA, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 3,883,000    
Investment, Identifier [Axis]: IDERA, Inc., Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,602,000    
Fair value, ending balance     4,602,000
Investment, Identifier [Axis]: IDERA, Inc., Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 933,000    
Fair value, ending balance     933,000
Investment, Identifier [Axis]: IDERA, Inc., Software, S+ 6.75% (10.56%)      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 716,000    
Investment, Identifier [Axis]: IG Investments Holdings, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: IG Investments Holdings, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 26,001,000    
Fair value, ending balance 25,935,000 [10],[11]   26,001,000 [8],[9]
Investment, Identifier [Axis]: ION Platform Finance US, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,803,000    
Fair value, ending balance 3,709,000   3,803,000
Investment, Identifier [Axis]: IQN Holding Corp. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 5,790,000    
Fair value, ending balance 5,748,000 [11]   5,790,000 [9]
Investment, Identifier [Axis]: IQN Holding Corp. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 988,000    
Fair value, ending balance 864,000 [11],[14]   988,000 [9],[15]
Investment, Identifier [Axis]: IQN Holding Corp. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 17,329,000    
Fair value, ending balance 17,159,000 [10],[11],[13]   17,329,000 [8],[9],[12]
Investment, Identifier [Axis]: Icon Parent I, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,981,000    
Fair value, ending balance 4,753,000   4,981,000
Investment, Identifier [Axis]: Ideal Tridon Holdings, Inc. | Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (72,000)    
Fair value, ending balance (69,000) [11],[14]   (72,000) [9],[15]
Investment, Identifier [Axis]: Ideal Tridon Holdings, Inc. | Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 804,000    
Fair value, ending balance 807,000 [11],[14]   804,000 [9],[15]
Investment, Identifier [Axis]: Ideal Tridon Holdings, Inc. | Machinery 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 41,876,000    
Fair value, ending balance 41,788,000 [10],[11],[13]   41,876,000 [8],[9],[12]
Investment, Identifier [Axis]: Indicor, LLC, Industrial Conglomerates      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,942,000    
Investment, Identifier [Axis]: Indigo Buyer, Inc. | Containers & Packaging 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 4,007,000    
Fair value, ending balance 9,788,000 [11],[14]   4,007,000 [9],[15]
Investment, Identifier [Axis]: Indigo Buyer, Inc. | Containers & Packaging 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Indigo Buyer, Inc. | Containers & Packaging 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 60,879,000    
Fair value, ending balance 60,725,000 [10],[11]   60,879,000 [8],[9]
Investment, Identifier [Axis]: InhabitIQ, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (31,000)    
Fair value, ending balance (109,000) [11],[14]   (31,000) [9],[15]
Investment, Identifier [Axis]: InhabitIQ, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (20,000)    
Fair value, ending balance (68,000) [11],[14]   (20,000) [9],[15]
Investment, Identifier [Axis]: InhabitIQ, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 25,897,000    
Fair value, ending balance 25,555,000 [10],[11],[13]   25,897,000 [8],[9],[12]
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc, Equity/Other Investments 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc. Electrical Equipment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[22],[24] 0    
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc. | Electrical Equipment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23] 1,378,000    
Fair value, ending balance [9],[23]     1,378,000
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc. | Electrical Equipment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23],[29] 668,000    
Fair value, ending balance [9],[23],[29]     668,000
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc. | Electrical Equipment 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 0    
Fair value, ending balance [7],[9],[16],[21]     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc. | Electrical Equipment 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 0    
Fair value, ending balance [7],[9],[16],[21]     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0    
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0    
Gross additions 0    
Gross reductions 0    
Realized Gain/(Loss) 0    
Change in Unrealized Gain (Loss) 0    
Fair value, ending balance 0   0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Equity/Other Investments 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Senior Secured First Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 8,000    
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,378,000    
Gross additions 0    
Gross reductions (1,378,000)    
Realized Gain/(Loss) (1,000)    
Change in Unrealized Gain (Loss) 1,000    
Fair value, ending balance 0   1,378,000
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Senior Secured First Lien Debt 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     105,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,378,000 1,393,000 1,393,000
Gross additions     0
Gross reductions     (15,000)
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     1,378,000
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Senior Secured First Lien Debt 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     10,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 210,000 210,000
Gross additions     150,000
Gross reductions     (360,000)
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Senior Secured First Lien Debt 3      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     17,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     240,000
Gross reductions     (249,000)
Realized Gain/(Loss)     9,000
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Integrated Efficiency Solutions, Inc., Senior Secured Second Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income (1,000)   1,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 668,000 446,000 446,000
Gross additions 0   0
Gross reductions (628,000)   0
Realized Gain/(Loss) (446,000)   0
Change in Unrealized Gain (Loss) 406,000   222,000
Fair value, ending balance 0   668,000
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Commercial Services & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (72,000)    
Fair value, ending balance [9],[15]     (72,000)
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 1,560,000    
Fair value, ending balance [9],[15]     1,560,000
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Commercial Services & Supplies 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 32,151,000    
Fair value, ending balance [8],[9],[12]     32,151,000
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Construction & Engineering 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (69,000)    
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Construction & Engineering 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 4,093,000    
Investment, Identifier [Axis]: Integrated Global Services, Inc. | Construction & Engineering 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 32,086,000    
Investment, Identifier [Axis]: International Cruise & Excursion Gallery, Inc. | Hotels, Restaurants & Leisure 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13] 1,358,000    
Investment, Identifier [Axis]: International Cruise & Excursion Gallery, Inc. | Hotels, Restaurants & Leisure 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[12],[16],[21] 0    
Fair value, ending balance 0 [11],[13],[18],[19]   0 [7],[9],[12],[16],[21]
Investment, Identifier [Axis]: International Cruise & Excursion Gallery, Inc. | Hotels, Restaurants & Leisure A      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[12] 1,358,000    
Fair value, ending balance [9],[12]     1,358,000
Investment, Identifier [Axis]: Invenergy Thermal Operating I, LLC, Independent Power and Renewable Electricity Producers      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,578,000    
Fair value, ending balance     3,578,000
Investment, Identifier [Axis]: Invenergy Thermal Operating I, LLC, Independent Power and Renewable Electricity Producers 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 3,463,000    
Investment, Identifier [Axis]: Invenergy Thermal Operating I, LLC, Independent Power and Renewable Electricity Producers 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 226,000    
Fair value, ending balance 225,000   226,000
Investment, Identifier [Axis]: Jane Street Group, LLC, Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 8,040,000    
Fair value, ending balance 7,906,000   8,040,000
Investment, Identifier [Axis]: Jump Financial, LLC, Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,124,000    
Fair value, ending balance 7,205,000   7,124,000
Investment, Identifier [Axis]: KKR Financial CLO, Ltd. 15 FR, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,795,000    
Fair value, ending balance 1,507,000   1,795,000
Investment, Identifier [Axis]: Kahala Aviation, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17] 33,911,000    
Fair value, ending balance [9],[17]     33,911,000
Investment, Identifier [Axis]: Kahala Aviation, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[17] 10,330,000    
Fair value, ending balance [7],[9],[16],[17]     10,330,000
Investment, Identifier [Axis]: Kahala Aviation, LLC | Asset Based Financing 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[20] 47,542,000    
Investment, Identifier [Axis]: Kahala Aviation, LLC | Asset Based Financing 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[20] 12,473,000    
Investment, Identifier [Axis]: Kahala Aviation, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 10,330,000 2,308,000 2,308,000
Gross additions 2,022,000   7,545,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 121,000   477,000
Fair value, ending balance 12,473,000   10,330,000
Investment, Identifier [Axis]: Kahala Aviation, LLC, Subordinated Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 1,270,000   3,360,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 33,911,000 0 0
Gross additions 13,496,000   33,874,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 135,000   37,000
Fair value, ending balance 47,542,000   33,911,000
Investment, Identifier [Axis]: Kahala Ireland Opco DAC, Subordinated Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Kahala US OpCo, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     83,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: Kaman Corp., Aerospace & Defense 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 58,000    
Fair value, ending balance 0   58,000
Investment, Identifier [Axis]: Kaman Corp., Aerospace & Defense 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,220,000    
Fair value, ending balance 6,297,000   6,220,000
Investment, Identifier [Axis]: Kaseya, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,772,000    
Fair value, ending balance 3,503,000   3,772,000
Investment, Identifier [Axis]: Kingpin Intermediate Holdings, LLC, Hotels, Restaurants & Leisure 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,733,000    
Fair value, ending balance 4,417,000   4,733,000
Investment, Identifier [Axis]: Kingpin Intermediate Holdings, LLC, Hotels, Restaurants & Leisure 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,331,000    
Fair value, ending balance 6,795,000   7,331,000
Investment, Identifier [Axis]: Knowledge Pro Buyer, Inc. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 21,622,000    
Fair value, ending balance 22,894,000 [11],[14]   21,622,000 [9],[15]
Investment, Identifier [Axis]: Knowledge Pro Buyer, Inc. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 2,976,000 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Knowledge Pro Buyer, Inc. | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 42,173,000    
Fair value, ending balance 41,975,000 [10],[11],[13]   42,173,000 [8],[9],[12]
Investment, Identifier [Axis]: Kodiak Building Partners, LLC, Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,896,000    
Fair value, ending balance 3,998,000   3,896,000
Investment, Identifier [Axis]: LABL, Inc., Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,093,000    
Fair value, ending balance 2,226,000   3,093,000
Investment, Identifier [Axis]: LBM Acquisition, LLC, Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 1,591,000    
Investment, Identifier [Axis]: LCM, Ltd. Partnership 16A ER2, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,807,000    
Fair value, ending balance 1,635,000   1,807,000
Investment, Identifier [Axis]: LSF12 Donnelly Bidco, LLC | Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 18,739,000    
Fair value, ending balance 18,691,000 [10],[11]   18,739,000 [8],[9]
Investment, Identifier [Axis]: Labrie Environmental Group, LLC | Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[26] 21,666,000    
Fair value, ending balance [9],[26]     21,666,000
Investment, Identifier [Axis]: Lakeland Tours, LLC | Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13],[30] 1,981,000    
Investment, Identifier [Axis]: Lakeland Tours, LLC | Diversified Consumer Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12],[29] 45,000    
Fair value, ending balance [8],[9],[12],[29]     45,000
Investment, Identifier [Axis]: Lakeland Tours, LLC | Diversified Consumer Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[12],[29] 1,414,000    
Fair value, ending balance 0 [11],[13],[18],[19]   1,414,000 [9],[12],[29]
Investment, Identifier [Axis]: LaserShip, Inc. | Air Freight & Logistics      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 742,000    
Investment, Identifier [Axis]: LaserShip, Inc. | Ground Transportation      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 838,000    
Fair value, ending balance     838,000
Investment, Identifier [Axis]: Last Dance Intermediate II, LLC | Diversified Telecommunication Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 3,987,000    
Fair value, ending balance 0 [11],[14]   3,987,000 [9],[15]
Investment, Identifier [Axis]: Last Dance Intermediate II, LLC | Diversified Telecommunication Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (44,000)    
Fair value, ending balance 15,250,000 [11],[14]   (44,000) [9],[15]
Investment, Identifier [Axis]: Last Dance Intermediate II, LLC | Diversified Telecommunication Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 18,884,000    
Fair value, ending balance 0 [11],[14]   18,884,000 [8],[9],[12]
Investment, Identifier [Axis]: Last Dance Intermediate II, LLC | Diversified Telecommunication Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 19,059,000    
Fair value, ending balance 19,054,000 [10],[11],[13]   19,059,000 [8],[9],[12]
Investment, Identifier [Axis]: Last Dance Intermediate II, LLC | Diversified Telecommunication Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 19,312,000    
Investment, Identifier [Axis]: Lighthouse Intelligence, Ltd. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[26] (154,000)    
Fair value, ending balance 22,093,000 [11],[25]   (154,000) [9],[15],[26]
Investment, Identifier [Axis]: Lighthouse Intelligence, Ltd. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[26] (110,000)    
Fair value, ending balance (345,000) [11],[14],[25]   (110,000) [9],[15],[26]
Investment, Identifier [Axis]: Lighthouse Intelligence, Ltd. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[26] 22,370,000    
Fair value, ending balance (246,000) [11],[14],[25]   22,370,000 [9],[26]
Investment, Identifier [Axis]: MGTF Holdco, LLC | Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[17],[21] 0    
Fair value, ending balance [7],[9],[16],[17],[21]     0
Investment, Identifier [Axis]: MGTF Holdco, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: MGTF Radio Company, LLC | Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17],[29] 11,408,000    
Fair value, ending balance [9],[17],[29]     11,408,000
Investment, Identifier [Axis]: MGTF Radio Company, LLC, Senior Secured First Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   1,116,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 11,408,000 31,672,000 31,672,000
Gross additions 0   103,000
Gross reductions (12,000,000)   0
Realized Gain/(Loss) (33,020,000)   0
Change in Unrealized Gain (Loss) 33,612,000   (20,367,000)
Fair value, ending balance 0   11,408,000
Investment, Identifier [Axis]: MH Sub I, LLC, IT Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,978,000    
Fair value, ending balance 4,589,000   4,978,000
Investment, Identifier [Axis]: MRI Software, LLC | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 52,000    
Fair value, ending balance 2,153,000 [11]   52,000 [9],[15]
Investment, Identifier [Axis]: MRI Software, LLC | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 11,000    
Fair value, ending balance 6,650,000 [11]   11,000 [9],[15]
Investment, Identifier [Axis]: MRI Software, LLC | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 2,180,000    
Fair value, ending balance 162,000 [11],[14]   2,180,000 [9]
Investment, Identifier [Axis]: MRI Software, LLC | Software 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 6,734,000    
Fair value, ending balance 14,000 [11],[14]   6,734,000 [9]
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Capital Markets 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 8,965,000    
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 929,000    
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Capital Markets 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 15,249,000    
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 1,941,000    
Fair value, ending balance [9],[15]     1,941,000
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (13,000)    
Fair value, ending balance [9],[15]     (13,000)
Investment, Identifier [Axis]: MWH Intermediate II, LLC | Financial Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 15,284,000    
Fair value, ending balance [8],[9]     15,284,000
Investment, Identifier [Axis]: Mandrake Bidco, Inc. | Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Mandrake Bidco, Inc. | Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 55,557,000    
Fair value, ending balance 55,557,000 [10],[11],[13]   55,557,000 [8],[9],[12]
Investment, Identifier [Axis]: Manna Pro Products, LLC | Food Products 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 3,373,000    
Investment, Identifier [Axis]: Manna Pro Products, LLC | Food Products 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (430,000)    
Investment, Identifier [Axis]: Manna Pro Products, LLC | Food Products 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13] 1,608,000    
Investment, Identifier [Axis]: Manna Pro Products, LLC | Food Products 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13] 5,783,000    
Investment, Identifier [Axis]: Manna Pro Products, LLC | Food Products 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13] 20,396,000    
Investment, Identifier [Axis]: Manna Pro Products, LLC | Specialty Retail 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 3,341,000    
Fair value, ending balance [9]     3,341,000
Investment, Identifier [Axis]: Manna Pro Products, LLC | Specialty Retail 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (430,000)    
Fair value, ending balance [9],[15]     (430,000)
Investment, Identifier [Axis]: Manna Pro Products, LLC | Specialty Retail 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,593,000    
Fair value, ending balance [9]     1,593,000
Investment, Identifier [Axis]: Manna Pro Products, LLC | Specialty Retail 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 5,729,000    
Fair value, ending balance [9]     5,729,000
Investment, Identifier [Axis]: Manna Pro Products, LLC | Specialty Retail 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 20,204,000    
Fair value, ending balance [9]     20,204,000
Investment, Identifier [Axis]: Max US Bidco, Inc., Food Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,755,000    
Fair value, ending balance 4,007,000   3,755,000
Investment, Identifier [Axis]: McDonald Worley, P.C. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[29] 6,513,000    
Fair value, ending balance 4,845,000 [11],[14],[30]   6,513,000 [9],[15],[29]
Investment, Identifier [Axis]: McDonald Worley, P.C. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 10,264,000    
Fair value, ending balance 10,828,000 [11],[18],[19]   10,264,000 [7],[9],[16]
Investment, Identifier [Axis]: Medical Management Resource Group, LLC | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 744,000    
Fair value, ending balance (28,000) [11],[14]   744,000 [9],[15]
Investment, Identifier [Axis]: Medical Management Resource Group, LLC | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 9,184,000    
Fair value, ending balance 9,160,000 [10],[11]   9,184,000 [8],[9]
Investment, Identifier [Axis]: Medical Management Resource Group, LLC | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 22,233,000    
Fair value, ending balance 22,175,000 [10],[11]   22,233,000 [8],[9]
Investment, Identifier [Axis]: Megavolt Borrower, LLC | Construction & Engineering      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 36,989,000    
Fair value, ending balance 36,896,000 [10],[11],[13]   36,989,000 [8],[9],[12]
Investment, Identifier [Axis]: Merlin Buyer, Inc., Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,118,000    
Fair value, ending balance     1,118,000
Investment, Identifier [Axis]: Merlin Buyer, Inc., Machinery 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 2,500,000    
Investment, Identifier [Axis]: Merlin Buyer, Inc., Machinery 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 1,105,000    
Investment, Identifier [Axis]: Mermaid Bidco Inc, IT Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,481,000    
Fair value, ending balance     7,481,000
Investment, Identifier [Axis]: Mermaid Bidco, Inc. , IT Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 7,276,000    
Investment, Identifier [Axis]: Michael Baker International, LLC | Construction & Engineering      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 17,155,000    
Investment, Identifier [Axis]: Michael Baker International, LLC | Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 18,223,000    
Fair value, ending balance [9]     18,223,000
Investment, Identifier [Axis]: Midwest Can Company, LLC | Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 27,902,000    
Fair value, ending balance 27,902,000 [10],[11],[13]   27,902,000 [8],[9],[12]
Investment, Identifier [Axis]: Mirra-Primeaccess Holdings, LLC | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 7,316,000    
Fair value, ending balance 61,120,000 [11]   7,316,000 [9],[15]
Investment, Identifier [Axis]: Mirra-Primeaccess Holdings, LLC | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 61,279,000    
Fair value, ending balance 7,316,000 [11],[14]   61,279,000 [9]
Investment, Identifier [Axis]: Monogram Food Solutions, LLC, Food Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,088,000    
Fair value, ending balance 2,082,000   2,088,000
Investment, Identifier [Axis]: Motor Vehicle Software Corp. | Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[31] 1,077,000    
Fair value, ending balance 1,077,000 [11],[18],[19],[32]   1,077,000 [7],[9],[16],[31]
Investment, Identifier [Axis]: Multi-Color Corp., Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 276,000    
Investment, Identifier [Axis]: Muth Mirror Systems, LLC | Automobile Components 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 0    
Fair value, ending balance [7],[9],[16],[21]     0
Investment, Identifier [Axis]: Muth Mirror Systems, LLC | Automobile Components 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[29] 396,000    
Fair value, ending balance 6,000 [11],[14],[30]   396,000 [9],[15],[29]
Investment, Identifier [Axis]: Muth Mirror Systems, LLC | Automobile Components 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[29] 7,624,000    
Fair value, ending balance 4,626,000 [11],[30]   7,624,000 [9],[29]
Investment, Identifier [Axis]: Muth Mirror Systems, LLC | Automobile Components 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 0    
Fair value, ending balance 0 [11],[18],[19],[22]   0 [7],[9],[16],[21]
Investment, Identifier [Axis]: Muth Mirror Systems, LLC | Automobile Components 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[22] 0    
Investment, Identifier [Axis]: Neptune Bidco US, Inc., Interactive Media & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 579,000    
Fair value, ending balance     579,000
Investment, Identifier [Axis]: NewStar Arlington Senior Loan Program, LLC 14-1A FR | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[23],[26] 4,322,000    
Fair value, ending balance 3,553,000 [11],[19],[24],[25]   4,322,000 [7],[9],[23],[26]
Investment, Identifier [Axis]: NewStar Arlington Senior Loan Program, LLC 14-1A FR, Collateralized Securities      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 193,000   794,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,322,000 4,237,000 4,237,000
Gross additions 15,000   48,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) (784,000)   37,000
Fair value, ending balance 3,553,000   4,322,000
Investment, Identifier [Axis]: NewStar Arlington Senior Loan Program, LLC 14-1A SUB | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[23],[26],[33] 0    
Fair value, ending balance 0 [11],[19],[24],[25],[34]   0 [7],[9],[23],[26],[33]
Investment, Identifier [Axis]: NewStar Arlington Senior Loan Program, LLC 14-1A SUB, Collateralized Securities      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   (88,000)
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 2,170,000 2,170,000
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   (2,170,000)
Fair value, ending balance 0   0
Investment, Identifier [Axis]: Newstar Fairfield Fund CLO, Ltd. 2015-1RA F, Collateralized Securities      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     17,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 2,457,000 2,457,000
Gross additions     3,000
Gross reductions     (2,457,000)
Realized Gain/(Loss)     137,000
Change in Unrealized Gain (Loss)     (140,000)
Fair value, ending balance     0
Investment, Identifier [Axis]: Newstar Fairfield Fund CLO, Ltd. 2015-1RA SUB | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[23],[26],[33] 477,000    
Fair value, ending balance 476,000 [11],[19],[24],[25],[34]   477,000 [7],[9],[23],[26],[33]
Investment, Identifier [Axis]: Newstar Fairfield Fund CLO, Ltd. 2015-1RA SUB, Collateralized Securities      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 477,000 1,208,000 1,208,000
Gross additions 0   0
Gross reductions (12,000)   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 11,000   (731,000)
Fair value, ending balance 476,000   477,000
Investment, Identifier [Axis]: Nexus Buyer, LLC , Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,750,000    
Investment, Identifier [Axis]: Nexus Buyer, LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,889,000    
Fair value, ending balance     4,889,000
Investment, Identifier [Axis]: Norvax, LLC | Insurance 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 354,000    
Fair value, ending balance 228,000 [11]   354,000 [9]
Investment, Identifier [Axis]: Norvax, LLC | Insurance 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 228,000    
Fair value, ending balance 360,000 [11]   228,000 [9]
Investment, Identifier [Axis]: Nouryon Finance B.V., Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,202,000    
Fair value, ending balance 2,151,000   2,202,000
Investment, Identifier [Axis]: ORG GC Holdings, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21],[23] 0    
Fair value, ending balance [7],[9],[16],[21],[23]     0
Investment, Identifier [Axis]: ORG GC Holdings, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23] 10,111,000    
Fair value, ending balance 10,111,000 [11],[24]   10,111,000 [9],[23]
Investment, Identifier [Axis]: ORG GC Holdings, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[23],[29] 2,810,000    
Fair value, ending balance 2,570,000 [11],[24],[30]   2,810,000 [9],[23],[29]
Investment, Identifier [Axis]: ORG GC Holdings, LLC | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21],[23] 0    
Fair value, ending balance 0 [11],[18],[19],[22],[24]   0 [7],[9],[16],[21],[23]
Investment, Identifier [Axis]: ORG GC Holdings, LLC | Professional Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[22],[24] 0    
Investment, Identifier [Axis]: ORG GC Holdings, LLC, Equity/Other Investments 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 0   0
Investment, Identifier [Axis]: ORG GC Holdings, LLC, Equity/Other Investments 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 0   0
Investment, Identifier [Axis]: ORG GC Holdings, LLC, Equity/Other Investments 3      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: ORG GC Holdings, LLC, Senior Secured First Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 263,000   1,124,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 10,111,000 10,112,000 10,112,000
Gross additions (2,000)   (3,000)
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 2,000   2,000
Fair value, ending balance 10,111,000   10,111,000
Investment, Identifier [Axis]: ORG GC Holdings, LLC, Senior Secured Second Lien Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   576,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,810,000 4,999,000 4,999,000
Gross additions 0   578,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) (240,000)   (2,767,000)
Fair value, ending balance 2,570,000   2,810,000
Investment, Identifier [Axis]: OSV Thunderbold Topco, Inc. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 4,548,000    
Investment, Identifier [Axis]: OSV Thunderbold Topco, Inc. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19] 0    
Investment, Identifier [Axis]: Odessa Technologies, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Odessa Technologies, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 20,236,000    
Fair value, ending balance 20,183,000 [10],[11]   20,236,000 [8],[9]
Investment, Identifier [Axis]: Omnia Partners, LLC , Commercial Services & Supplies      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,171,000    
Fair value, ending balance     6,171,000
Investment, Identifier [Axis]: Omnia Partners, LLC, Commercial Services & Supplies      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 6,125,000    
Investment, Identifier [Axis]: One Source Virtual, Inc. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (13,000)    
Investment, Identifier [Axis]: OneSource Virtual, Inc. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 18,874,000    
Investment, Identifier [Axis]: PG&E Corp., Electric Utilities      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,412,000    
Fair value, ending balance 9,868,000   9,412,000
Investment, Identifier [Axis]: PODS, LLC, Air Freight & Logistics      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,343,000    
Fair value, ending balance 7,369,000   7,343,000
Investment, Identifier [Axis]: Palmdale Oil Co., LLC | Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 3,335,000    
Fair value, ending balance 4,328,000 [11]   3,335,000 [9]
Investment, Identifier [Axis]: Peer Holding III B.V., Broadline Retail      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,961,000    
Fair value, ending balance 5,907,000   5,961,000
Investment, Identifier [Axis]: PennantPark Credit Opportunities Fund II, LP | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[16],[23],[26] 552,000    
Fair value, ending balance 718,000 [18],[19],[24],[25]   552,000 [7],[16],[23],[26]
Investment, Identifier [Axis]: PennantPark Credit Opportunities Fund II, LP, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 552,000 603,000 603,000
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 166,000   (51,000)
Fair value, ending balance 718,000   552,000
Investment, Identifier [Axis]: Peraton Corp., Communications Equipment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,636,000    
Fair value, ending balance     7,636,000
Investment, Identifier [Axis]: Peraton Corp., Communications Equipment, S+ 7.75% (11.52%)      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 6,971,000    
Investment, Identifier [Axis]: PetSmart, LLC, Specialty Retail      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,442,000    
Fair value, ending balance 2,436,000   2,442,000
Investment, Identifier [Axis]: PetVet Care Centers, LLC | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 210,000    
Fair value, ending balance 403,000   210,000 [9],[15]
Investment, Identifier [Axis]: PetVet Care Centers, LLC | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 28,841,000    
Fair value, ending balance 27,196,000 [10],[11],[13]   28,841,000 [8],[9],[12]
Investment, Identifier [Axis]: Pie Buyer, Inc. | Consumer Staples Distribution & Retail 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 2,323,000    
Fair value, ending balance 1,893,000 [11],[14]   2,323,000 [9]
Investment, Identifier [Axis]: Pie Buyer, Inc. | Consumer Staples Distribution & Retail 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 7,787,000    
Fair value, ending balance 7,787,000 [10],[11]   7,787,000 [8],[9]
Investment, Identifier [Axis]: Pie Buyer, Inc. | Consumer Staples Distribution & Retail 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 2,042,000    
Fair value, ending balance 2,042,000 [10],[11]   2,042,000 [8],[9]
Investment, Identifier [Axis]: Pie Buyer, Inc. | Consumer Staples Distribution & Retail 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 35,981,000    
Fair value, ending balance 35,982,000 [10],[11],[13]   35,981,000 [8],[9],[12]
Investment, Identifier [Axis]: Pie Buyer, Inc. | Consumer Staples Distribution & Retail 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 2,660,000    
Fair value, ending balance 2,654,000 [10],[11],[13]   2,660,000 [8],[9],[12]
Investment, Identifier [Axis]: Pluralsight, LLC | Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance [7],[9],[16]     0
Investment, Identifier [Axis]: Pluralsight, LLC | Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19] 0    
Investment, Identifier [Axis]: Pluralsight, LLC | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 4,600,000    
Fair value, ending balance 4,569,000 [11]   4,600,000 [9]
Investment, Identifier [Axis]: Pluralsight, LLC | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 7,422,000    
Fair value, ending balance 2,321,000 [11]   7,422,000 [9]
Investment, Identifier [Axis]: Pluralsight, LLC | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 2,336,000    
Fair value, ending balance (26,000) [11],[14]   2,336,000 [9]
Investment, Identifier [Axis]: Pluralsight, LLC | Software 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (11,000)    
Investment, Identifier [Axis]: Pluralsight, LLC | Software 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[30] 822,000    
Investment, Identifier [Axis]: Pluto Acquisition I, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,337,000    
Fair value, ending balance 3,329,000   3,337,000
Investment, Identifier [Axis]: Pluto Acquisition I, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 32,134,000    
Fair value, ending balance 32,134,000 [10],[11]   32,134,000 [8],[9]
Investment, Identifier [Axis]: Pluto Acquisition I, Inc., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,984,000    
Fair value, ending balance 8,358,000   7,984,000
Investment, Identifier [Axis]: Point Broadband Acquisition, LLC | Diversified Telecommunication Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 124,000    
Fair value, ending balance [7],[9],[16],[21]     124,000
Investment, Identifier [Axis]: Point Broadband Acquisition, LLC | Diversified Telecommunication Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[16],[21] 4,935,000    
Fair value, ending balance [9],[16],[21]     4,935,000
Investment, Identifier [Axis]: Point Broadband Acquisition, LLC | Diversified Telecommunication Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[22] 124,000    
Investment, Identifier [Axis]: Point Broadband Acquisition, LLC | Diversified Telecommunication Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19],[22] 4,935,000    
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[19],[20],[22],[28] 128,252,000    
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[17],[27] 0    
Fair value, ending balance [9],[15],[17],[27]     0
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[17],[21],[27] 128,252,000    
Fair value, ending balance [7],[9],[17],[21],[27]     128,252,000
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[17],[27] 34,000,000    
Fair value, ending balance 3,000,000 [11],[14],[20],[28]   34,000,000 [9],[15],[17],[27]
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[20],[28] 35,000,000    
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC | Asset Based Financing 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17],[27] 62,601,000    
Fair value, ending balance 62,600,000 [11],[20],[28]   62,601,000 [9],[17],[27]
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 2,920,000   11,274,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 128,252,000 119,233,000 119,233,000
Gross additions 0   8,926,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   93,000
Fair value, ending balance 128,252,000   128,252,000
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC, Subordinated Debt 1      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 1,801,000   7,595,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 62,601,000 62,599,000 62,599,000
Gross additions 7,000   (2,000)
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) (8,000)   4,000
Fair value, ending balance 62,600,000   62,601,000
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC, Subordinated Debt 2      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 980,000   3,864,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 34,000,000 35,000,000 35,000,000
Gross additions 1,000,000   23,000,000
Gross reductions 0   (24,000,000)
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 0   0
Fair value, ending balance 35,000,000   34,000,000
Investment, Identifier [Axis]: Post Road Equipment Finance, LLC, Subordinated Debt 3      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 18,000   190,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 3,000,000 3,000,000
Gross additions 3,000,000   10,000,000
Gross reductions (15,000)   (13,050,000)
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 15,000   50,000
Fair value, ending balance 3,000,000   0
Investment, Identifier [Axis]: Pregis TopCo, LLC, Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,712,000    
Fair value, ending balance 6,631,000   6,712,000
Investment, Identifier [Axis]: Pretzel Parent, Inc, Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 3,404,000    
Investment, Identifier [Axis]: Pretzel Parent, Inc., Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,426,000    
Fair value, ending balance     3,426,000
Investment, Identifier [Axis]: Primo Brands Corp., Beverages      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 6,141,000    
Investment, Identifier [Axis]: ProAmpac PG Borrower, LLC, Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 6,802,000    
Investment, Identifier [Axis]: Proofpoint, Inc, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 6,379,000    
Investment, Identifier [Axis]: Proofpoint, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,644,000    
Fair value, ending balance     6,644,000
Investment, Identifier [Axis]: Pug, LLC, Entertainment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,474,000    
Fair value, ending balance 5,400,000   2,474,000
Investment, Identifier [Axis]: Questex, Inc. | Media 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (32,000)    
Fair value, ending balance (32,000) [11],[14]   (32,000) [9],[15]
Investment, Identifier [Axis]: Questex, Inc. | Media 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[12] 14,703,000    
Fair value, ending balance 14,665,000 [11],[13]   14,703,000 [9],[12]
Investment, Identifier [Axis]: Quikrete Holdings, Inc., Construction Materials 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,517,000    
Fair value, ending balance 4,485,000   4,517,000
Investment, Identifier [Axis]: Quikrete Holdings, Inc., Construction Materials 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,538,000    
Fair value, ending balance 2,518,000   2,538,000
Investment, Identifier [Axis]: RMP Group, Inc. | Health Care Technology      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[21] 246,000    
Fair value, ending balance 54,000 [11],[18],[19],[22]   246,000 [7],[9],[16],[21]
Investment, Identifier [Axis]: Radiology Partners, Inc, Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 7,446,000    
Investment, Identifier [Axis]: Radiology Partners, Inc., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,570,000    
Fair value, ending balance     7,570,000
Investment, Identifier [Axis]: Raven Acquisition Holdings, LLC, Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,754,000    
Fair value, ending balance 9,506,000   9,754,000
Investment, Identifier [Axis]: Raven Acquisition Holdings, LLC, Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,000    
Fair value, ending balance (14,000)   2,000
Investment, Identifier [Axis]: Reagent Chemical and Research, LLC | Chemicals 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 5,605,000    
Fair value, ending balance 5,311,000 [11]   5,605,000 [9]
Investment, Identifier [Axis]: Reagent Chemical and Research, LLC | Chemicals 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Reagent Chemical and Research, LLC | Chemicals 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 44,417,000    
Fair value, ending balance 43,370,000 [10],[11],[13]   44,417,000 [8],[9],[12]
Investment, Identifier [Axis]: Recess Holdings, Inc., Household Durables      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,373,000    
Fair value, ending balance 5,336,000   5,373,000
Investment, Identifier [Axis]: Red Planet Borrower, LLC, Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,506,000    
Fair value, ending balance 7,305,000   7,506,000
Investment, Identifier [Axis]: Relativity Oda, LLC | Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 7,717,000    
Fair value, ending balance [8],[9]     7,717,000
Investment, Identifier [Axis]: Renaissance Holdings Corp., Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,613,000    
Fair value, ending balance 2,921,000   3,613,000
Investment, Identifier [Axis]: Resideo Funding, Inc., Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,934,000    
Fair value, ending balance 1,894,000   1,934,000
Investment, Identifier [Axis]: Resilience Parent, LLC | Electrical Equipment      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11] 13,483,000    
Investment, Identifier [Axis]: Resolute Investment Managers, Inc. | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19] 2,022,000    
Investment, Identifier [Axis]: Resolute Investment Managers, Inc. | Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 2,022,000    
Fair value, ending balance [7],[9],[16]     2,022,000
Investment, Identifier [Axis]: Resolute Investment Managers, Inc., Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 991,000    
Investment, Identifier [Axis]: Resolute Investment Managers, Inc., Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 991,000    
Fair value, ending balance     991,000
Investment, Identifier [Axis]: Rialto Management Group, LLC | Capital Markets 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Rialto Management Group, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 20,178,000    
Investment, Identifier [Axis]: Rialto Management Group, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: Rialto Management Group, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 20,178,000    
Fair value, ending balance [8],[9],[12]     20,178,000
Investment, Identifier [Axis]: Rithum Holdings, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,977,000    
Fair value, ending balance 4,720,000   4,977,000
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Construction & Engineering 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 7,286,000    
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Construction & Engineering 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 6,779,000    
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Construction & Engineering 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 11,930,000    
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Construction & Engineering 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 1,075,000    
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Transportation Infrastructure 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 7,286,000    
Fair value, ending balance [8],[9]     7,286,000
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Transportation Infrastructure 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 6,779,000    
Fair value, ending balance [8],[9]     6,779,000
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Transportation Infrastructure 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 11,930,000    
Fair value, ending balance [8],[9],[12]     11,930,000
Investment, Identifier [Axis]: Roadsafe Holdings, Inc. | Transportation Infrastructure 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 1,075,000    
Fair value, ending balance [8],[9],[12]     1,075,000
Investment, Identifier [Axis]: Roper Industrial Products Investment Co., LLC, Industrial Conglomerates      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,973,000    
Fair value, ending balance     4,973,000
Investment, Identifier [Axis]: S&S Holdings, LLC, Textiles, Apparel & luxury goods      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,668,000    
Fair value, ending balance 4,398,000   4,668,000
Investment, Identifier [Axis]: SCIH Salt Holdings, Inc. | Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 315,000    
Fair value, ending balance (15,000) [11],[14]   315,000 [9],[15]
Investment, Identifier [Axis]: Saab Purchaser, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (166,000)    
Fair value, ending balance (166,000) [11],[14]   (166,000) [9],[15]
Investment, Identifier [Axis]: Saab Purchaser, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (22,000)    
Fair value, ending balance (22,000) [11],[14]   (22,000) [9],[15]
Investment, Identifier [Axis]: Saab Purchaser, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 17,705,000    
Fair value, ending balance 17,705,000 [10],[11]   17,705,000 [8],[9]
Investment, Identifier [Axis]: Saranac CLO, Ltd. 20-8A E, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,095,000    
Fair value, ending balance 673,000   1,095,000
Investment, Identifier [Axis]: Saturn SHC Buyer Holdings, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (1,290,000)    
Fair value, ending balance (2,580,000) [11],[14]   (1,290,000) [9],[15]
Investment, Identifier [Axis]: Saturn SHC Buyer Holdings, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 33,449,000    
Fair value, ending balance 29,733,000 [10],[11]   33,449,000 [8],[9]
Investment, Identifier [Axis]: Saturn SHC Buyer Holdings, Inc. | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 11,693,000    
Fair value, ending balance 10,394,000 [10],[11]   11,693,000 [8],[9]
Investment, Identifier [Axis]: Saturn Sound Bidco, Ltd. | Aerospace & Defense 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14],[25] 0    
Investment, Identifier [Axis]: Saturn Sound Bidco, Ltd. | Aerospace & Defense 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[13],[14],[25] 24,800,000    
Investment, Identifier [Axis]: Saturn Sound Bidco, Ltd. | Trading Companies & Distributors 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15],[26] (38,000)    
Fair value, ending balance [9],[15],[26]     (38,000)
Investment, Identifier [Axis]: Saturn Sound Bidco, Ltd. | Trading Companies & Distributors 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12],[26] 24,589,000    
Fair value, ending balance [8],[9],[12],[26]     24,589,000
Investment, Identifier [Axis]: Sedgwick Claims Management Services, Inc., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,239,000    
Fair value, ending balance 7,060,000   7,239,000
Investment, Identifier [Axis]: Sharp Services, LLC, Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,023,000    
Fair value, ending balance 3,006,000   3,023,000
Investment, Identifier [Axis]: Sherlock Buyer Corp. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 15,558,000    
Fair value, ending balance [8],[9],[12]     15,558,000
Investment, Identifier [Axis]: Sherlock Buyer Corp. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Sherlock Buyer Corp. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 15,516,000    
Investment, Identifier [Axis]: Siena Capital Finance, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[19],[20] 83,997,000    
Investment, Identifier [Axis]: Siena Capital Finance, LLC | Asset Based Financing      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[17] 77,728,000    
Fair value, ending balance 83,500,000 [11],[20]   77,728,000 [7],[9],[17]
Investment, Identifier [Axis]: Siena Capital Finance, LLC | Asset Based Financing 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[17] 77,500,000    
Fair value, ending balance [9],[17]     77,500,000
Investment, Identifier [Axis]: Siena Capital Finance, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 2,762,000   13,727,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 77,728,000 77,310,000 77,310,000
Gross additions 0   0
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 6,269,000   418,000
Fair value, ending balance 83,997,000   77,728,000
Investment, Identifier [Axis]: Siena Capital Finance, LLC, Subordinated Debt      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 2,437,000   7,109,000
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 77,500,000 49,500,000 49,500,000
Gross additions 6,011,000   27,990,000
Gross reductions 0   0
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) (11,000)   10,000
Fair value, ending balance 83,500,000   77,500,000
Investment, Identifier [Axis]: Simplifi Holdings, Inc. | Media 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 49,524,000    
Fair value, ending balance [8],[9]     49,524,000
Investment, Identifier [Axis]: Simplifi Holdings, Inc. | Media 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 516,000    
Fair value, ending balance 2,132,000 [11],[14]   516,000 [9],[15]
Investment, Identifier [Axis]: Simplifi Holdings, Inc. | Media 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 49,396,000    
Investment, Identifier [Axis]: SitusAMC Holdings Corp. | Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11],[13] 51,999,000    
Investment, Identifier [Axis]: SitusAMC Holdings Corp. | Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 52,130,000    
Fair value, ending balance [8],[9],[12]     52,130,000
Investment, Identifier [Axis]: Skillsoft Corp. | Professional Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [16] 116,000    
Fair value, ending balance [16]     116,000
Investment, Identifier [Axis]: Smile Brands, Inc. | Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: Smile Brands, Inc. | Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[30] 0    
Investment, Identifier [Axis]: Smile Brands, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 9,000    
Fair value, ending balance [9]     9,000
Investment, Identifier [Axis]: Sonrava Health Holdings, LLC, Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,754,000    
Fair value, ending balance 1,754,000   1,754,000
Investment, Identifier [Axis]: Sonrava Health Holdings, LLC, Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,617,000    
Fair value, ending balance 317,000   1,617,000
Investment, Identifier [Axis]: Sonrava Health Holdings, LLC, Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 311,000    
Fair value, ending balance 1,639,000   311,000
Investment, Identifier [Axis]: Sotera Health Holdings, LLC, Life Sciences Tools & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,442,000    
Fair value, ending balance 7,391,000   7,442,000
Investment, Identifier [Axis]: Sound Point CLO, Ltd. 17-2A E, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 1,820,000    
Fair value, ending balance 1,540,000   1,820,000
Investment, Identifier [Axis]: Sound Point CLO, Ltd. 18-3A D, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 819,000    
Fair value, ending balance 637,000   819,000
Investment, Identifier [Axis]: Specialty Building Products Holdings, LLC, Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,583,000    
Fair value, ending balance 5,427,000   4,583,000
Investment, Identifier [Axis]: Squan Holding Corp. | Wireless Telecommunication Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[18],[19] 0    
Investment, Identifier [Axis]: Squan Holding Corp. | Wireless Telecommunication Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance [7],[9],[16]     0
Investment, Identifier [Axis]: Staples, Inc., Business Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 704,292,000    
Fair value, ending balance     704,292,000
Investment, Identifier [Axis]: Staples, Inc., Specialty Retail      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,799,000    
Fair value, ending balance 2,672,000   2,799,000
Investment, Identifier [Axis]: Starlight Parent, LLC, Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,472,000    
Fair value, ending balance 4,624,000   5,472,000
Investment, Identifier [Axis]: Stonepeak Nile Parent, LLC , Air Freight & Logistics      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,373,000    
Fair value, ending balance     4,373,000
Investment, Identifier [Axis]: Stonepeak Nile Parent, LLC, Air Freight & Logistics      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,352,000    
Investment, Identifier [Axis]: Striper Buyer, LLC | Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 16,093,000    
Investment, Identifier [Axis]: Striper Buyer, LLC | Containers & Packaging      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 16,652,000    
Fair value, ending balance [8],[9]     16,652,000
Investment, Identifier [Axis]: SunMed Group Holdings, LLC | Health Care Equipment & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: SunMed Group Holdings, LLC | Health Care Equipment & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 12,438,000    
Fair value, ending balance 12,405,000 [10],[11]   12,438,000 [8],[9]
Investment, Identifier [Axis]: Symphony CLO, Ltd. 2012-9A ER2, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,779,000    
Fair value, ending balance 2,389,000   2,779,000
Investment, Identifier [Axis]: TEI Intermediate, LLC | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 859,000    
Fair value, ending balance [9],[15]     859,000
Investment, Identifier [Axis]: TEI Intermediate, LLC | Commercial Services & Supplies 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 932,000    
Fair value, ending balance 4,771,000 [11],[14]   932,000 [9],[15]
Investment, Identifier [Axis]: TEI Intermediate, LLC | Commercial Services & Supplies 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 859,000    
Investment, Identifier [Axis]: TEI Intermediate, LLC | Commercial Services & Supplies 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 23,015,000    
Fair value, ending balance 23,180,000 [10],[11],[13]   23,015,000 [8],[9],[12]
Investment, Identifier [Axis]: TK Elevator Midco GmbH, Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 3,604,000    
Investment, Identifier [Axis]: Tax Defense Network, LLC | Diversified Consumer Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[29] 0    
Fair value, ending balance 0 [11],[30]   0 [9],[29]
Investment, Identifier [Axis]: Tax Defense Network, LLC | Diversified Consumer Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[29] 0    
Fair value, ending balance 0 [11],[30]   0 [9],[29]
Investment, Identifier [Axis]: Tax Defense Network, LLC | Diversified Consumer Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[29] 6,022,000    
Fair value, ending balance 6,203,000 [11],[30]   6,022,000 [9],[29]
Investment, Identifier [Axis]: Tax Defense Network, LLC | Diversified Consumer Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: Tax Defense Network, LLC | Diversified Consumer Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: Tecta America Corp., Construction & Engineering      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,485,000    
Fair value, ending balance 5,430,000   5,485,000
Investment, Identifier [Axis]: Tennenbaum Waterman Fund, LP | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[16],[23],[26] 461,000    
Fair value, ending balance 465,000 [18],[19],[24],[25]   461,000 [7],[16],[23],[26]
Investment, Identifier [Axis]: Tennenbaum Waterman Fund, LP, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income 0   0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 461,000 5,802,000 5,802,000
Gross additions 0   0
Gross reductions 0   (5,020,000)
Realized Gain/(Loss) 0   0
Change in Unrealized Gain (Loss) 4,000   (321,000)
Fair value, ending balance 465,000   461,000
Investment, Identifier [Axis]: The NPD Group, LP | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: The NPD Group, LP | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 52,102,000    
Fair value, ending balance 52,102,000 [10],[11]   52,102,000 [8],[9]
Investment, Identifier [Axis]: Therapy Brands Holdings, LLC | Health Care Technology 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 5,565,000    
Fair value, ending balance 5,550,000 [10],[11]   5,565,000 [8],[9]
Investment, Identifier [Axis]: Therapy Brands Holdings, LLC | Health Care Technology 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 4,786,000    
Fair value, ending balance 5,677,000 [10],[11]   4,786,000 [8],[9]
Investment, Identifier [Axis]: Tivity Health, Inc. | Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 24,229,000    
Investment, Identifier [Axis]: Tivity Health, Inc. | Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 24,291,000    
Fair value, ending balance [8],[9]     24,291,000
Investment, Identifier [Axis]: TransDigm, Inc., Aerospace & Defense      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,914,000    
Fair value, ending balance 3,890,000   3,914,000
Investment, Identifier [Axis]: Travelpro Products, Inc. | Textiles, Apparel & luxury goods      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[26] 183,000    
Fair value, ending balance 134,000 [11],[18],[19],[25]   183,000 [7],[9],[16],[26]
Investment, Identifier [Axis]: Traverse Midstream Partners, LLC, Oil, Gas & Consumable Fuels      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,859,000    
Fair value, ending balance 9,841,000   9,859,000
Investment, Identifier [Axis]: Trinity Air Consultants Holdings Corp. | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 16,184,000 [11]   0 [9],[15]
Investment, Identifier [Axis]: Trinity Air Consultants Holdings Corp. | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Trinity Air Consultants Holdings Corp. | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 16,224,000    
Fair value, ending balance 0 [11],[14]   16,224,000 [9]
Investment, Identifier [Axis]: Triple Lift, Inc. | Media 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (282,000)    
Fair value, ending balance (282,000) [11],[14]   (282,000) [9],[15]
Investment, Identifier [Axis]: Triple Lift, Inc. | Media 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 36,635,000    
Fair value, ending balance 36,539,000 [10],[11],[13]   36,635,000 [8],[9],[12]
Investment, Identifier [Axis]: Triton Water Holdings, Inc., Beverages      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,402,000    
Fair value, ending balance     7,402,000
Investment, Identifier [Axis]: Truck Hero, Inc, Automobile Components 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 3,025,000    
Investment, Identifier [Axis]: Truck Hero, Inc, Automobile Components 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 5,596,000    
Investment, Identifier [Axis]: Truck Hero, Inc., Automobile Components 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,428,000    
Fair value, ending balance     3,428,000
Investment, Identifier [Axis]: Truck Hero, Inc., Automobile Components 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,391,000    
Fair value, ending balance     6,391,000
Investment, Identifier [Axis]: Trystar, LLC | Electrical Equipment 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 2,926,000    
Fair value, ending balance 12,583,000 [11]   2,926,000 [9],[15]
Investment, Identifier [Axis]: Trystar, LLC | Electrical Equipment 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Trystar, LLC | Electrical Equipment 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 24,549,000    
Fair value, ending balance 22,896,000 [10],[11],[13]   24,549,000 [8],[9],[12]
Investment, Identifier [Axis]: Trystar, LLC | Electrical Equipment 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[12] 10,364,000    
Fair value, ending balance 10,338,000 [11],[13]   10,364,000 [9],[12]
Investment, Identifier [Axis]: UKG, Inc., Software      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 9,642,000    
Fair value, ending balance 9,173,000   9,642,000
Investment, Identifier [Axis]: US Anesthesia Partners, Inc., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 6,938,000    
Fair value, ending balance 6,890,000   6,938,000
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 6,098,000    
Fair value, ending balance [8],[9]     6,098,000
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 5,050,000    
Fair value, ending balance 5,050,000 [11]   5,050,000 [9]
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 6,997,000    
Fair value, ending balance 6,997,000 [10],[11]   6,997,000 [8],[9]
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 6,098,000    
Investment, Identifier [Axis]: US Oral Surgery Management Holdco, LLC | Health Care Providers & Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 17,668,000    
Fair value, ending balance 17,668,000 [10],[11]   17,668,000 [8],[9]
Investment, Identifier [Axis]: US Salt Investors, LLC | Chemicals 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14],[25] 16,514,000    
Investment, Identifier [Axis]: US Salt Investors, LLC | Chemicals 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14],[25] (19,000)    
Investment, Identifier [Axis]: US Salt Investors, LLC | Metals & Mining 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance [9],[15]     0
Investment, Identifier [Axis]: US Salt Investors, LLC | Metals & Mining 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 25,657,000    
Fair value, ending balance [8],[9]     25,657,000
Investment, Identifier [Axis]: United Airlines, Inc., Passenger Airlines      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,722,000    
Fair value, ending balance 3,685,000   3,722,000
Investment, Identifier [Axis]: University Support Services, LLC , Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,882,000    
Fair value, ending balance     3,882,000
Investment, Identifier [Axis]: University Support Services, LLC, Diversified Consumer Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,906,000    
Investment, Identifier [Axis]: Urban One, Inc. | Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7] 235,000    
Fair value, ending balance [7]     235,000
Investment, Identifier [Axis]: Urban One, Inc. | Media 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[19] 157,000    
Investment, Identifier [Axis]: Urban One, Inc. | Media 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [19] 365,000    
Investment, Identifier [Axis]: VFH Parent, LLC, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,010,000    
Fair value, ending balance 4,942,000   5,010,000
Investment, Identifier [Axis]: Vanco Payment Solutions, LLC | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (5,000)    
Fair value, ending balance 11,120,000 [11]   (5,000) [9],[15]
Investment, Identifier [Axis]: Vanco Payment Solutions, LLC | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (5,000)    
Investment, Identifier [Axis]: Vanco Payment Solutions, LLC| Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 11,147,000    
Fair value, ending balance [9]     11,147,000
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 5,423,000    
Fair value, ending balance [9]     5,423,000
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 5,825,000 [11]   0 [9],[15]
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (21,000)    
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance (43,000) [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance (54,000) [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Varicent Intermediate Holdings Corp. | Software 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 21,107,000    
Fair value, ending balance 20,906,000 [10],[11],[13]   21,107,000 [8],[9],[12]
Investment, Identifier [Axis]: Venture CLO 43, Ltd. 21-43A E, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 2,715,000    
Fair value, ending balance 1,917,000   2,715,000
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 1,551,000    
Fair value, ending balance 2,976,000 [11]   1,551,000 [9]
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 944,000 [11]   0 [9],[15]
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 23,455,000    
Fair value, ending balance 1,547,000 [11]   23,455,000 [8],[9]
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 5      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] 0    
Investment, Identifier [Axis]: Victors CCC Buyer, LLC | Professional Services 6      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 23,395,000    
Investment, Identifier [Axis]: Victory Buyer, LLC | Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 45,990,000    
Fair value, ending balance [8],[9]     45,990,000
Investment, Identifier [Axis]: Victory Buyer, LLC | Machinery      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] 37,949,000    
Investment, Identifier [Axis]: Victory Buyer, LLC, Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,375,000    
Fair value, ending balance     7,375,000
Investment, Identifier [Axis]: WCG Intermediate Corp., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance 4,341,000    
Investment, Identifier [Axis]: WCG Purchaser Corp., Health Care Providers & Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,479,000    
Fair value, ending balance     4,479,000
Investment, Identifier [Axis]: WHCG Purchaser III, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 24,091,000    
Fair value, ending balance 24,397,000 [11]   24,091,000 [9]
Investment, Identifier [Axis]: WHCG Purchaser III, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[29] 9,645,000    
Fair value, ending balance 9,882,000 [11],[30]   9,645,000 [9],[29]
Investment, Identifier [Axis]: WHCG Purchaser III, Inc. | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: WIN Holdings III Corp. | Diversified Consumer Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 1,192,000    
Fair value, ending balance 1,192,000 [11],[14]   1,192,000 [9],[15]
Investment, Identifier [Axis]: WIN Holdings III Corp. | Diversified Consumer Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 41,683,000    
Fair value, ending balance 41,683,000 [10],[11]   41,683,000 [8],[9]
Investment, Identifier [Axis]: WIN Holdings III Corp. | Diversified Consumer Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 9,915,000    
Fair value, ending balance 9,890,000 [10],[11]   9,915,000 [8],[9]
Investment, Identifier [Axis]: WIN Holdings III Corp. | Diversified Consumer Services 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 20,255,000    
Fair value, ending balance 20,204,000 [10],[11]   20,255,000 [8],[9]
Investment, Identifier [Axis]: WPNT, LLC | Media      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16],[17],[21] 0    
Fair value, ending balance [7],[9],[16],[17],[21]     0
Investment, Identifier [Axis]: WPNT, LLC, Equity/Other Investments      
Investments in and Advances to Affiliates [Line Items]      
Amount of dividends and interest included in income     0
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 0 $ 0 0
Gross additions     0
Gross reductions     0
Realized Gain/(Loss)     0
Change in Unrealized Gain (Loss)     0
Fair value, ending balance     0
Investment, Identifier [Axis]: West Coast Dental Services, Inc. | Health Care Providers & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 2,898,000    
Fair value, ending balance 2,901,000 [11],[14]   2,898,000 [9],[15]
Investment, Identifier [Axis]: West Coast Dental Services, Inc. | Health Care Providers & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 1,332,000    
Fair value, ending balance 1,328,000 [10],[11]   1,332,000 [8],[9]
Investment, Identifier [Axis]: West Coast Dental Services, Inc. | Health Care Providers & Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 22,299,000    
Fair value, ending balance 22,242,000 [10],[11]   22,299,000 [8],[9]
Investment, Identifier [Axis]: WestJet Loyalty, LP, Passenger Airlines      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,718,000    
Fair value, ending balance 5,508,000   5,718,000
Investment, Identifier [Axis]: Westwood Professional Services, Inc. | Construction & Engineering 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 4,429,000    
Fair value, ending balance 4,417,000 [11],[14]   4,429,000 [9],[15]
Investment, Identifier [Axis]: Westwood Professional Services, Inc. | Construction & Engineering 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] 0    
Fair value, ending balance 0 [11],[14]   0 [9],[15]
Investment, Identifier [Axis]: Westwood Professional Services, Inc. | Construction & Engineering 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9],[12] 44,848,000    
Fair value, ending balance 44,735,000 [10],[11],[13]   44,848,000 [8],[9],[12]
Investment, Identifier [Axis]: Wharf Street Ratings Acquisition, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (28,000)    
Fair value, ending balance [9],[15]     (28,000)
Investment, Identifier [Axis]: Wharf Street Ratings Acquisition, LLC | Capital Markets 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (28,000)    
Fair value, ending balance (26,000) [11],[14]   (28,000) [9],[15]
Investment, Identifier [Axis]: Wharf Street Ratings Acquisition, LLC | Capital Markets 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (26,000)    
Investment, Identifier [Axis]: Wharf Street Ratings Acquisition, LLC | Capital Markets 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 25,550,000    
Fair value, ending balance 25,496,000 [10],[11]   25,550,000 [8],[9]
Investment, Identifier [Axis]: White Cap Supply Holdings, LLC, Building Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 5,301,000    
Fair value, ending balance 5,054,000   5,301,000
Investment, Identifier [Axis]: Whitehorse, Ltd. 14-1A E | Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[26] 62,000    
Fair value, ending balance 69,000 [11],[19],[25]   62,000 [7],[9],[26]
Investment, Identifier [Axis]: Wind River CLO, Ltd. 14-2A FR, Capital Markets      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 91,000    
Fair value, ending balance 179,000   91,000
Investment, Identifier [Axis]: Windsor Holdings III, LLC, Chemicals      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 3,249,000    
Fair value, ending balance 3,184,000   3,249,000
Investment, Identifier [Axis]: Wipfli Advisory, LLC | Financial Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (14,000)    
Fair value, ending balance (14,000) [11],[14]   (14,000) [9],[15]
Investment, Identifier [Axis]: Wipfli Advisory, LLC | Financial Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9],[15] (19,000)    
Fair value, ending balance (19,000) [11],[14]   (19,000) [9],[15]
Investment, Identifier [Axis]: Wipfli Advisory, LLC | Financial Services 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 16,057,000    
Fair value, ending balance 16,059,000 [10],[11]   16,057,000 [8],[9]
Investment, Identifier [Axis]: World Business Lenders, LLC | Financial Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 1,615,000    
Fair value, ending balance 3,967,000 [11],[18],[19]   1,615,000 [7],[9],[16]
Investment, Identifier [Axis]: X Corp., Interactive Media & Services 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,857,000    
Fair value, ending balance     4,857,000
Investment, Identifier [Axis]: X Corp., Interactive Media & Services 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 7,468,000    
Fair value, ending balance     7,468,000
Investment, Identifier [Axis]: YummyEarth, Inc. | Food Products      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [7],[9],[16] 0    
Fair value, ending balance 0 [11],[18],[19]   0 [7],[9],[16]
Investment, Identifier [Axis]: Zayo Group Holdings, Inc., Diversified Telecommunication Services      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance 4,242,000    
Fair value, ending balance 5,871,000   4,242,000
Investment, Identifier [Axis]: Zendesk, Inc. | Software 1      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [9] 10,462,000    
Fair value, ending balance 5,390,000 [11]   10,462,000 [9]
Investment, Identifier [Axis]: Zendesk, Inc. | Software 2      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, beginning balance [8],[9] 64,884,000    
Fair value, ending balance 10,268,000 [11]   $ 64,884,000 [8],[9]
Investment, Identifier [Axis]: Zendesk, Inc. | Software 3      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [11],[14] (105,000)    
Investment, Identifier [Axis]: Zendesk, Inc. | Software 4      
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]      
Fair value, ending balance [10],[11] $ 63,689,000    
[1] Percentages are based on net assets attributable to common stock as of December 31, 2025.
[2] Unless otherwise indicated, all investments in the consolidated schedules of investments are non-affiliated, non-controlled investments.
[3] Unless otherwise indicated, all of the Company's investments or a portion thereof are pledged as collateral under the JPM Revolver Facility (as defined below).
[4] Percentages are based on net assets attributable to common stock as of March 31, 2026.
[5] Unless otherwise indicated, all investments in the consolidated schedules of investments are non-affiliated, non-controlled investments.
[6] Unless otherwise indicated, all of the Company's investments or a portion thereof are pledged as collateral under the JPM Revolver Facility.
[7] Securities exempt from registration under the Securities Act of 1933 (as defined below), and may be deemed to be “restricted securities.” As of December 31, 2025, the aggregate fair value of these securities is $523.7 million or 28.5% of the Company’s net assets. The initial acquisition dates have been included for such securities.
[8] The Company's investment or a portion thereof is pledged as collateral under the JPM Credit Facility (as defined below).
[9] The fair value of investments with respect to securities for which market quotations are not readily available is determined in good faith by the Company's Board of Directors (as defined below) as required by the 1940 Act. Such investments are valued using significant unobservable inputs (See Note 3 to the consolidated financial statements).
[10] The Company's investment or a portion thereof is pledged as collateral under the JPM Credit Facility.
[11] The fair value of investments with respect to securities for which market quotations are not readily available is determined in good faith by the Company's Board of Directors (as defined below) as required by the 1940 Act. Such investments are valued using significant unobservable inputs (See Note 3 to the consolidated financial statements).
[12] The Company's investment or a portion thereof is pledged as collateral under the Wells Fargo Credit Facility. Individual investments can be divided into parts which are pledged to separate credit facilities.
[13] The Company's investment or a portion thereof is pledged as collateral under the Wells Fargo Credit Facility (as defined below). Individual investments can be divided into parts which are pledged to separate credit facilities.
[14] Position or portion thereof is an unfunded loan commitment, and no interest is being earned on the unfunded portion. The investment may be subject to an unused/letter of credit facility fee. The negative fair value, if applicable, is the result of the capitalized discount on the loan or the unfunded commitment being valued below par. The negative amortized cost, if applicable, is the result of the capitalized discount being greater than the principal amount outstanding on the loan. Please refer to Note 7 - Commitments and Contingencies for additional details.
[15] Position or portion thereof is an unfunded loan commitment, and no interest is being earned on the unfunded portion. The investment may be subject to an unused/letter of credit facility fee. The negative fair value, if applicable, is the result of the capitalized discount on the loan or the unfunded commitment being valued below par. The negative amortized cost, if applicable, is the result of the capitalized discount being greater than the principal amount outstanding on the loan. Please refer to Note 7 - Commitments and Contingencies for additional details.
[16] Non-income producing at December 31, 2025.
[17] The provisions of the 1940 Act classify investments based on the level of control that the Company maintains in a particular portfolio company. As defined in the 1940 Act, a company is generally presumed to be “non-controlled” when the Company owns 25% or less of the portfolio company’s outstanding voting securities and/or does not have the power to exercise control over the management or policies of such portfolio company. A company is generally presumed to be “controlled” when the Company owns more than 25% of the portfolio company’s outstanding voting securities and/or has the power to exercise control over the management or policies of such portfolio company. The Company classifies this investment as “controlled.”
[18] Non-income producing at March 31, 2026.
[19] Securities exempt from registration under the Securities Act of 1933 (as defined below), and may be deemed to be “restricted securities.” As of March 31, 2026, the aggregate fair value of these securities is $533.7 million or 29.1% of the Company’s net assets. The initial acquisition dates have been included for such securities.
[20] The provisions of the 1940 Act classify investments based on the level of control that the Company maintains in a particular portfolio company. As defined in the 1940 Act, a company is generally presumed to be “non-controlled” when the Company owns 25% or less of the portfolio company’s outstanding voting securities and/or does not have the power to exercise control over the management or policies of such portfolio company. A company is generally presumed to be “controlled” when the Company owns more than 25% of the portfolio company’s outstanding voting securities and/or has the power to exercise control over the management or policies of such portfolio company. The Company classifies this investment as “controlled.”
[21] Investments are held in the taxable wholly-owned, consolidated subsidiary, 54th Street Equity Holdings, Inc.
[22] Investments are held in the taxable wholly-owned, consolidated subsidiary, 54th Street Equity Holdings, Inc.
[23] The provisions of the 1940 Act classify investments further based on the level of ownership that the Company maintains in a particular portfolio company. As defined in the 1940 Act, a company is generally deemed as "non-affiliated" when the Company owns less than 5% of a portfolio company's outstanding voting securities and "affiliated" when the Company owns 5% or more of a portfolio company's outstanding voting securities. The Company classifies this investment as “affiliated.”
[24] The provisions of the 1940 Act classify investments further based on the level of ownership that the Company maintains in a particular portfolio company. As defined in the 1940 Act, a company is generally deemed as "non-affiliated" when the Company owns less than 5% of a portfolio company's outstanding voting securities and "affiliated" when the Company owns 5% or more of a portfolio company's outstanding voting securities. The Company classifies this investment as “affiliated.”
[25] All of the Company's investments, except the investments noted by this footnote, are qualifying assets under Section 55(a) of the Investment Company Act of 1940, as amended (the “1940 Act”). Under the 1940 Act, the Company may not acquire any non-qualifying asset unless, at the time the acquisition is made, qualifying assets represent at least 70% of the Company's total assets. At March 31, 2026, qualifying assets represent 92.3% of the Company's total assets.
[26] All of the Company's investments, except the investments noted by this footnote, are qualifying assets under Section 55(a) of the Investment Company Act of 1940, as amended (the “1940 Act”). Under the 1940 Act, the Company may not acquire any non-qualifying asset unless, at the time the acquisition is made, qualifying assets represent at least 70% of the Company's total assets. At December 31, 2025, qualifying assets represent 92.2% of the Company's total assets.
[27] The Company's investment falls under the definition of a significant subsidiary, as it exceeded the threshold of at least one of the tests under Rule 4-08(g), or exceeded the threshold of at least one of the tests under Rule 3-09. See Note 3 for summarized financial information.
[28] The Company's investment falls under the definition of a significant subsidiary, as it exceeded the threshold of at least one of the tests under Rule 4-08(g), or exceeded the threshold of at least one of the tests under Rule 3-09. See Note 3 for summarized financial information.
[29] The investment is on non-accrual status as of December 31, 2025.
[30] The investment is on non-accrual status as of March 31, 2026.
[31] The investment is held through BSP TCAP Acquisition Holdings LP, which is an affiliated acquisition entity. Due to certain restrictions, such as limits on the number of partners allowable within the equity structures of the newly acquired investments, these investments are still held within the acquisition entity as of December 31, 2025.
[32] The investment is held through BSP TCAP Acquisition Holdings LP, which is an affiliated acquisition entity. Due to certain restrictions, such as limits on the number of partners allowable within the equity structures of the newly acquired investments, these investments are still held within the acquisition entity as of March 31, 2026.
[33] The Collateralized Securities - subordinated notes are treated as equity investments and are entitled to recurring distributions which are generally equal to the remaining cash flow of the payments made by the underlying fund’s securities less contractual payments to debt holders and fund expenses. The estimated yield indicated is based upon a current projection of the amount and timing of these recurring distributions and the estimated amount of repayment of principal upon termination. Such projections are periodically reviewed and adjusted, and the estimated yield may not ultimately be realized.
[34] The Collateralized Securities - subordinated notes are treated as equity investments and are entitled to recurring distributions which are generally equal to the remaining cash flow of the payments made by the underlying fund’s securities less contractual payments to debt holders and fund expenses. The estimated yield indicated is based upon a current projection of the amount and timing of these recurring distributions and the estimated amount of repayment of principal upon termination. Such projections are periodically reviewed and adjusted, and the estimated yield may not ultimately be realized.