v3.26.3
FAIR VALUE OF FINANCIAL INSTRUMENTS - Schedule of Fair Value Measurements of Cash and Cash Equivalents and Investments (Details) - USD ($)
Sep. 30, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments $ 21,355,776,100 [1] $ 21,508,598,400 [2]
Unfunded revolving and delayed draw loan commitments (35,634,000) (10,885,000)
Derivatives (200,818,000) (40,014,000)
Foreign currency forward contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 8,273,000 (22,867,000)
Interest rate swaps    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives (193,333,000) 58,008,000
First lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 16,263,640,000 17,160,266,000
Second lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 349,181,000 429,160,000
Senior subordinated loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,315,808,000 1,068,842,000
Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 62,294,000 99,063,000
Collateralized loan obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 714,587,000 1,051,264,000
Commercial mortgage-backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 109,642,000 99,962,000
Private asset-backed investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 327,901,000 300,947,000
Investments in joint ventures    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,003,200,000 391,000,000
Preferred equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 466,777,000 317,476,000
Total    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 21,250,513,000 21,407,501,000
Total | First lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 16,263,640,000 17,160,266,000
Total | Second lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 349,181,000 429,160,000
Total | Senior subordinated loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,315,808,000 1,068,842,000
Total | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 62,294,000 99,063,000
Total | Collateralized loan obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 714,587,000 1,051,264,000
Total | Commercial mortgage-backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 109,642,000 99,962,000
Total | Private asset-backed investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 327,901,000 300,947,000
Total | Investments in joint ventures    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,003,200,000 391,000,000
Total | Preferred equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 466,777,000 317,476,000
Total | Other equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 637,483,000 489,521,000
Level 1    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Unfunded revolving and delayed draw loan commitments 0 0
Level 1 | Foreign currency forward contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 0 0
Level 1 | Interest rate swaps    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 0 0
Level 1 | First lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Second lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Senior subordinated loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Collateralized loan obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Commercial mortgage-backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Private asset-backed investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Investments in joint ventures    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Preferred equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 1 | Other equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,238,307,000 6,909,693,000
Unfunded revolving and delayed draw loan commitments 0 0
Level 2 | Foreign currency forward contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 8,273,000 (22,867,000)
Level 2 | Interest rate swaps    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives (193,333,000) 58,008,000
Level 2 | First lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,033,886,000 6,617,396,000
Level 2 | Second lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 190,643,000 287,211,000
Level 2 | Senior subordinated loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,929,000 5,086,000
Level 2 | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 | Collateralized loan obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 | Commercial mortgage-backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 | Private asset-backed investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 | Investments in joint ventures    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 0 0
Level 2 | Preferred equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 9,892,000 0
Level 2 | Other equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,957,000 0
Level 3    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 17,012,206,000 14,497,808,000
Unfunded revolving and delayed draw loan commitments (35,634,000) (10,885,000)
Level 3 | Foreign currency forward contracts    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 0 0
Level 3 | Interest rate swaps    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Derivatives 0 0
Level 3 | First lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 12,229,754,000 10,542,870,000
Level 3 | Second lien senior secured loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 158,538,000 141,949,000
Level 3 | Senior subordinated loans    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,313,879,000 1,063,756,000
Level 3 | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 62,294,000 99,063,000
Level 3 | Collateralized loan obligations    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 714,587,000 1,051,264,000
Level 3 | Commercial mortgage-backed securities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 109,642,000 99,962,000
Level 3 | Private asset-backed investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 327,901,000 300,947,000
Level 3 | Investments in joint ventures    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,003,200,000 391,000,000
Level 3 | Preferred equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 456,885,000 317,476,000
Level 3 | Other equity    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 635,526,000 489,521,000
Measured at NAV    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments $ 105,263,000 $ 101,097,000
[1] As of September 30, 2026, the estimated net unrealized loss for federal tax purposes was approximately $128.4 million based on a tax cost basis of approximately $21.5 billion. As of September 30, 2026, the estimated aggregate gross unrealized loss for federal income tax purposes was approximately $518.0 million and the estimated aggregate gross unrealized gain for federal income tax purposes was $389.6 million.
[2] As of December 31, 2025, the estimated net unrealized gain for federal tax purposes was approximately $206.8 million based on a tax cost basis of approximately $21.3 billion. As of December 31, 2025, the estimated aggregate gross unrealized gain for federal income tax purposes was $354.9 million and the estimated aggregate gross unrealized loss for federal income tax purposes was $148.1 million.