v3.26.1
Investment Portfolio - Schedule of Investment Portfolio at Cost and Fair Value (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Schedule of Investments [Line Items]    
Amortized Cost $ 13,377.9 [1] $ 13,740.8 [2]
Fair Value $ 12,269.4 [1],[3] $ 13,008.6 [2],[4]
Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 100.00% 100.00%
Senior Secured Loans—First Lien    
Schedule of Investments [Line Items]    
Amortized Cost $ 7,746.2 [1] $ 7,819.4 [2]
Fair Value $ 7,310.1 [1],[3] $ 7,523.4 [2],[4]
Senior Secured Loans—First Lien | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 59.60% 57.80%
Senior Secured Loans—Second Lien    
Schedule of Investments [Line Items]    
Amortized Cost $ 593.0 $ 598.0
Fair Value $ 459.0 $ 539.0
Senior Secured Loans—Second Lien | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 3.80% 4.20%
Other Senior Secured Debt    
Schedule of Investments [Line Items]    
Amortized Cost $ 65.0 $ 65.0
Fair Value $ 36.0 $ 55.0
Other Senior Secured Debt | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 0.30% 0.40%
Subordinated Debt    
Schedule of Investments [Line Items]    
Amortized Cost $ 99.5 [1] $ 122.0
Fair Value $ 98.8 [1],[3] $ 126.0
Subordinated Debt | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 0.80% 1.00%
Asset Based Finance    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,826.2 [1] $ 1,830.9 [2]
Fair Value $ 1,660.4 [1],[3] $ 1,693.7 [2],[4]
Asset Based Finance | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 13.50% 13.00%
Credit Opportunities Partners JV, LLC    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,984.1 [1] $ 2,201.9 [2]
Fair Value $ 1,706.7 [1],[3] $ 1,967.9 [2],[4]
Credit Opportunities Partners JV, LLC | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 13.90% 15.10%
Equity/Other    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,064.0 $ 1,104.0
Fair Value $ 998.0 $ 1,104.0
Equity/Other | Percentage of Portfolio | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Percentage of Portfolio 8.10% 8.50%
[1] Security may be an obligation of one or more entities affiliated with the named company.
[2] Security may be an obligation of one or more entities affiliated with the named company.
[3] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.
[4] See Note 8 for additional information regarding the fair value of the Company’s financial instruments.