v3.26.1
FAIR VALUE MEASUREMENTS - Schedule of Reconciliation of the Beginning and Ending Balances for Investments (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Total        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance $ 2,113,153 $ 1,548,687 $ 1,866,214 $ 1,392,791
Purchase of investments 949,010 122,341 1,216,040 327,777
Proceeds from principal repayments and sales of investments (123,934) (67,502) (143,649) (124,180)
Payment-in-kind interest 2,414 1,638 4,729 3,183
Amortization of premium/accretion of discount, net 1,025 699 2,139 1,858
Transfers out of level 3 (54,569) (23,033) (50,912) (15,929)
Transfers to level 3 13,809 1,920 19,189 6,169
Ending balance 2,891,833 1,578,317 2,891,833 1,578,317
Net change in unrealized appreciation (depreciation) on non-controlled/non-affiliated company investments still held (9,724) (6,158) (21,790) (11,650)
Total | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings 412 (2,798) (327) (2,574)
Total | Income Statement Location [Axis]: us-gaap:UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings (9,487) (3,635) (21,590) (10,778)
First-Lien Debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 1,972,627 1,416,119 1,738,850 1,270,084
Purchase of investments 887,873 119,231 1,141,987 316,850
Proceeds from principal repayments and sales of investments (114,927) (53,866) (134,567) (110,538)
Payment-in-kind interest 594 143 1,434 177
Amortization of premium/accretion of discount, net 844 608 1,815 1,644
Transfers out of level 3 (54,569) (13,801) (50,320) (7,980)
Transfers to level 3 13,809 1,920 19,189 6,169
Ending balance 2,698,336 1,463,396 2,698,336 1,463,396
Net change in unrealized appreciation (depreciation) on non-controlled/non-affiliated company investments still held (8,430) (6,685) (19,785) (11,162)
First-Lien Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings 346 (2,837) (394) (2,613)
First-Lien Debt | Income Statement Location [Axis]: us-gaap:UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings (8,261) (4,121) (19,658) (10,397)
Subordinated Debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 111,569 111,897 107,783 102,993
Purchase of investments 48,617 1,512 51,295 9,320
Proceeds from principal repayments and sales of investments (9,007) (13,636) (9,013) (13,642)
Payment-in-kind interest 1,820 1,495 3,295 3,006
Amortization of premium/accretion of discount, net 181 91 324 214
Transfers out of level 3 0 0 0 0
Transfers to level 3 0 0 0 0
Ending balance 153,016 101,193 153,016 101,193
Net change in unrealized appreciation (depreciation) on non-controlled/non-affiliated company investments still held (298) (164) (802) (844)
Subordinated Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings 66 39 67 39
Subordinated Debt | Income Statement Location [Axis]: us-gaap:UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings (230) (205) (735) (737)
Equity Investments        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 28,957 20,671 19,581 19,714
Purchase of investments 12,520 1,598 22,758 1,607
Proceeds from principal repayments and sales of investments 0 0 (69) 0
Payment-in-kind interest 0 0 0 0
Amortization of premium/accretion of discount, net 0 0 0 0
Transfers out of level 3 0 (9,232) (592) (7,949)
Transfers to level 3 0 0 0 0
Ending balance 40,481 13,728 40,481 13,728
Net change in unrealized appreciation (depreciation) on non-controlled/non-affiliated company investments still held (996) 691 (1,203) 356
Equity Investments | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings 0 0 0 0
Equity Investments | Income Statement Location [Axis]: us-gaap:UnrealizedGainLossInvestmentDerivativeAndForeignCurrencyTransactionOperatingAfterTax        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gains or losses included in earnings $ (996) $ 691 $ (1,197) $ 356