v3.26.3
Fair Value Measurements - Changes in Fair Value of Investments Measured Using Level 3 Inputs (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Jun. 30, 2026
Dec. 31, 2025
Jun. 30, 2025
Dec. 31, 2024
Total                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Fair value, beginning of period $ 12,868,345 $ 13,595,554 $ 12,868,345 $ 13,595,554 $ 13,282,835 $ 14,100,239 $ 13,036,526 $ 12,976,765
Purchases of investments 381,684 1,033,870 1,148,555 2,300,878        
Proceeds from principal repayments and sales of investments (762,803) (435,950) (2,020,883) (1,598,191)        
Accretion of discount (amortization of premium) 12,006 13,018 35,961 39,619        
Transfers into level 3 0 8,360 0 8,585        
Transfers out of level 3 0 0 (9,146) (102,175)        
Fair value, end of period 12,868,345 13,595,554 12,868,345 13,595,554        
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations 190,606 (56,012) (103,551) (27,067)        
Investments, Realized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) (233,944) (9,270) (264,205) (1,977)        
Investments, Unrealized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) 188,567 (51,000) (122,176) (27,950)        
First lien debt                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Fair value, beginning of period 12,330,802 13,257,332 12,330,802 13,257,332 12,863,118 13,759,817 12,800,357 12,714,636
Purchases of investments 255,650 928,219 925,793 2,190,326        
Proceeds from principal repayments and sales of investments (754,802) (434,248) (2,001,125) (1,562,430)        
Accretion of discount (amortization of premium) 11,846 12,913 35,509 39,343        
Transfers into level 3 0 8,360 0 8,585        
Transfers out of level 3 0 0 (9,146) (102,175)        
Fair value, end of period 12,330,802 13,257,332 12,330,802 13,257,332        
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations 194,982 (54,660) (85,573) (25,068)        
Debt Securities, First Lien, Realized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) (237,953) (9,270) (276,518) (9,292)        
Debt Securities, First Lien, Unrealized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) 192,943 (48,999) (103,528) (21,661)        
Second lien debt                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Fair value, beginning of period 252,721 226,249 252,721 226,249 250,182 231,650 122,942 119,184
Purchases of investments 3,368 104,168 28,482 107,954        
Proceeds from principal repayments and sales of investments (779) (196) (2,819) (3,206)        
Accretion of discount (amortization of premium) 150 94 423 244        
Transfers into level 3 0 0 0 0        
Transfers out of level 3 0 0 0 0        
Fair value, end of period 252,721 226,249 252,721 226,249        
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations (198) (759) (5,020) 1,588        
Debt Securities, Second Lien, Realized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) (2) 0 5 (1)        
Debt Securities, Second Lien, Unrealized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) (198) (759) (5,020) 2,074        
Unsecured debt                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Fair value, beginning of period 12,498 13,991 12,498 13,991 12,348 12,278 13,721 33,521
Purchases of investments 537 487 1,963 1,426        
Proceeds from principal repayments and sales of investments (11) 0 (11) (20,595)        
Accretion of discount (amortization of premium) 10 11 29 32        
Transfers into level 3 0 0 0 0        
Transfers out of level 3 0 0 0 0        
Fair value, end of period 12,498 13,991 12,498 13,991        
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations (391) (228) (1,766) (663)        
Unsecured Debt, Realized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) 5 0 5 0        
Unsecured Debt, Unrealized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) (391) (228) (1,766) (393)        
Investments in equity                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Fair value, beginning of period 272,324 97,982 272,324 97,982 $ 157,187 $ 96,494 $ 99,506 $ 109,424
Purchases of investments 122,129 996 192,317 1,172        
Proceeds from principal repayments and sales of investments (7,211) (1,506) (16,928) (11,960)        
Accretion of discount (amortization of premium) 0 0 0 0        
Transfers into level 3 0 0 0 0        
Transfers out of level 3 0 0 0 0        
Fair value, end of period 272,324 97,982 272,324 97,982        
Net change in unrealized appreciation (depreciation) included in earnings related to financial instruments, included in net unrealized appreciation (depreciation) on the condensed consolidated statements of operations (3,787) (365) (11,192) (2,924)        
Equity Securities, Realized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) 4,006 0 12,303 7,316        
Equity Securities, Unrealized Gain (Loss)                
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                
Net realized gain (loss) $ (3,787) $ (1,014) $ (11,862) $ (7,970)