v3.26.3
INVESTMENTS - Investments (Details)
$ in Millions
 9 Months Ended 12 Months Ended
Sep. 30, 2026
USD ($)
borrower
Dec. 31, 2025
USD ($)
borrower
Schedule of Investments [Line Items]    
Amortized Cost $ 29,477.5 [1] $ 29,249.9 [2]
Fair Value $ 29,212.6 [1] $ 29,484.8 [2]
Loans on non-accrual status, as a percent of total investments at amortized cost 2.40% 1.80%
Loans on non-accrual status, as a percent of total investments at fair value 1.40% 1.20%
Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 100.00% 100.00%
Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 100.00% 100.00%
Senior Direct Lending Program    
Schedule of Investments [Line Items]    
Number of borrowers | borrower 73 39
Ivy Hill Asset Management, L.P.    
Schedule of Investments [Line Items]    
Amortized Cost $ 3,863.0 $ 3,190.0
Fair Value $ 13,910.0 $ 11,599.0
Number of borrowers | borrower 25  
Midwest | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 23.10% 22.90%
West | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 20.70% 20.30%
West | Senior Direct Lending Program | Investments, At Fair Value | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 3.90% 3.80%
West | Ivy Hill Asset Management, L.P. | Investments, At Fair Value | Customer Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 10.40% 8.30%
Northeast | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 18.10% 15.10%
Southeast | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 16.30% 18.80%
Mid-Atlantic | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 14.90% 16.30%
International | Investments, At Fair Value | Geographic Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 6.90% 6.60%
Software and Services    
Schedule of Investments [Line Items]    
Amortized Cost $ 6,661.9 $ 7,030.9
Fair Value $ 6,303.8 $ 7,032.3
Software and Services | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 21.60% 23.80%
Financial Services    
Schedule of Investments [Line Items]    
Amortized Cost $ 3,993.8 $ 3,434.9
Fair Value $ 4,229.9 $ 3,664.3
Financial Services | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 14.60% 12.40%
Health Care Equipment and Services    
Schedule of Investments [Line Items]    
Amortized Cost $ 3,263.9 $ 3,472.0
Fair Value $ 2,939.3 $ 3,333.5
Health Care Equipment and Services | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 10.10% 11.30%
Commercial and Professional Services    
Schedule of Investments [Line Items]    
Amortized Cost $ 2,795.8 $ 2,806.9
Fair Value $ 2,734.5 $ 2,776.7
Commercial and Professional Services | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 9.40% 9.40%
Consumer Services    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,826.0 $ 1,641.7
Fair Value $ 1,823.9 $ 1,663.4
Consumer Services | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 6.20% 5.60%
Insurance    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,555.3 $ 1,457.4
Fair Value $ 1,649.9 $ 1,521.4
Insurance | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 5.60% 5.20%
Consumer Distribution and Retail    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,460.6 $ 1,449.9
Fair Value $ 1,396.3 $ 1,424.7
Consumer Distribution and Retail | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 4.80% 4.80%
Capital Goods    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,215.8 $ 1,288.4
Fair Value $ 1,326.3 $ 1,349.9
Capital Goods | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 4.50% 4.60%
Investment Funds and Vehicles    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,160.7 $ 1,120.8
Fair Value $ 1,197.0 $ 1,142.0
Investment Funds and Vehicles | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 4.10% 3.90%
Sports, Media and Entertainment    
Schedule of Investments [Line Items]    
Amortized Cost $ 1,050.1 $ 1,150.3
Fair Value $ 1,151.0 $ 1,191.6
Sports, Media and Entertainment | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 3.90% 4.00%
Pharmaceuticals, Biotechnology and Life Sciences    
Schedule of Investments [Line Items]    
Amortized Cost $ 725.4 $ 800.4
Fair Value $ 713.9 $ 794.9
Pharmaceuticals, Biotechnology and Life Sciences | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 2.40% 2.70%
Materials    
Schedule of Investments [Line Items]    
Amortized Cost $ 706.1 $ 665.5
Fair Value $ 685.6 $ 656.6
Materials | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 2.30% 2.20%
Consumer Durables and Apparel    
Schedule of Investments [Line Items]    
Amortized Cost $ 563.5 $ 577.2
Fair Value $ 585.4 $ 583.9
Consumer Durables and Apparel | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 2.00% 2.00%
Independent Power and Renewable Electricity Producers    
Schedule of Investments [Line Items]    
Amortized Cost $ 387.3 $ 581.2
Fair Value $ 459.4 $ 642.7
Independent Power and Renewable Electricity Producers | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 1.60% 2.20%
Food and Beverage    
Schedule of Investments [Line Items]    
Amortized Cost $ 350.7 $ 343.2
Fair Value $ 333.2 $ 326.3
Food and Beverage | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 1.10% 1.10%
Other | Investments, At Fair Value | Industry Concentration Risk    
Schedule of Investments [Line Items]    
Composition, percent of fair value 5.80% 4.80%
First lien senior secured loans    
Schedule of Investments [Line Items]    
Amortized Cost $ 17,426.0 $ 18,103.0
Fair Value 16,871.0 17,858.0
Second lien senior secured loans    
Schedule of Investments [Line Items]    
Amortized Cost 1,301.0 1,558.0
Fair Value 1,172.0 1,487.0
Subordinated certificates of the SDLP    
Schedule of Investments [Line Items]    
Amortized Cost 1,140.0 1,103.0
Fair Value 1,153.0 1,117.0
Senior subordinated loans    
Schedule of Investments [Line Items]    
Amortized Cost 1,991.0 1,690.0
Fair Value 1,915.0 1,585.0
Preferred equity    
Schedule of Investments [Line Items]    
Amortized Cost 2,672.0 2,597.0
Fair Value 2,440.0 2,475.0
Ivy Hill Asset Management, L.P.    
Schedule of Investments [Line Items]    
Amortized Cost 2,886.0 2,231.0
Fair Value 3,066.0 2,434.0
Other equity    
Schedule of Investments [Line Items]    
Amortized Cost 2,062.0 1,968.0
Fair Value 2,596.0 2,529.0
Unitranche loans    
Schedule of Investments [Line Items]    
Amortized Cost 13,615.0 11,349.0
Fair Value $ 13,289.0 $ 11,239.0
[1] As of September 30, 2026, the estimated net unrealized gain for federal tax purposes was approximately $0.1 billion based on a tax cost basis of approximately $29.3 billion. As of September 30, 2026, the estimated aggregate gross unrealized gain for federal income tax purposes was approximately $1.6 billion and the estimated aggregate gross unrealized loss for federal income tax purposes was approximately $1.5 billion.     
[2] As of December 31, 2025, the estimated net unrealized gain for federal tax purposes was approximately $300 million based on a tax cost basis of $29.2 billion. As of December 31, 2025, the estimated aggregate gross unrealized gain for federal income tax purposes was approximately $1.3 billion and the estimated aggregate gross unrealized loss for federal income tax purposes was approximately $1.0 billion.