v3.25.1
Investment Portfolio - Schedule of Investment Portfolio, at Fair Value and Percentage (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2025
Dec. 31, 2024
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 14,121.5 [1] $ 13,490.4 [2]
Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 100.00% 100.00%
Automobiles & Components    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 4.0 $ 4.0
Automobiles & Components | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.00% 0.00%
Banks    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 0.0 $ 5.0
Banks | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.00% 0.00%
Capital Goods    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 1,781.0 $ 1,712.0
Capital Goods | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 12.60% 12.70%
Commercial & Professional Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 1,766.0 $ 1,733.0
Commercial & Professional Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 12.50% 12.80%
Consumer Discretionary Distribution & Retail    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 136.0 $ 174.0
Consumer Discretionary Distribution & Retail | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 1.00% 1.30%
Consumer Durables & Apparel    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 284.0 $ 229.0
Consumer Durables & Apparel | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 2.00% 1.70%
Consumer Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 255.0 $ 244.0
Consumer Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 1.80% 1.80%
Consumer Staples Distribution & Retail    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 101.0 $ 102.0
Consumer Staples Distribution & Retail | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.70% 0.80%
Credit Opportunities Partners JV, LLC    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 1,661.0 $ 1,363.0
Credit Opportunities Partners JV, LLC | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 11.80% 10.10%
Energy    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 81.0 $ 89.0
Energy | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.60% 0.70%
Equity Real Estate Investment Trusts (REITs)    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 238.0 $ 278.0
Equity Real Estate Investment Trusts (REITs) | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 1.70% 2.10%
Financial Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 1,093.0 $ 998.0
Financial Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 7.70% 7.40%
Food, Beverage & Tobacco    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 135.0 $ 113.0
Food, Beverage & Tobacco | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.90% 0.80%
Health Care Equipment & Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 1,652.0 $ 1,667.0
Health Care Equipment & Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 11.70% 12.40%
Household & Personal Products    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 131.0 $ 134.0
Household & Personal Products | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.90% 1.00%
Insurance    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 716.0 $ 735.0
Insurance | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 5.10% 5.40%
Materials    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 284.0 $ 334.0
Materials | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 2.00% 2.50%
Media & Entertainment    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 673.0 $ 699.0
Media & Entertainment | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 4.80% 5.20%
Pharmaceuticals, Biotechnology & Life Sciences    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 322.0 $ 298.0
Pharmaceuticals, Biotechnology & Life Sciences | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 2.30% 2.20%
Real Estate Management & Development    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 53.0 $ 27.0
Real Estate Management & Development | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.40% 0.20%
Software & Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 2,296.0 $ 2,187.0
Software & Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 16.20% 16.20%
Technology Hardware & Equipment    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 2.0 $ 2.0
Technology Hardware & Equipment | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.00% 0.00%
Telecommunication Services    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 67.0 $ 69.0
Telecommunication Services | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 0.50% 0.50%
Transportation    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Fair Value $ 391.0 $ 294.0
Transportation | Percentage  of Portfolio | Industry Concentration Risk    
Investment Company, Nonconsolidated Subsidiary [Line Items]    
Percentage of Portfolio 2.80% 2.20%
[1] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.
[2] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.