v3.26.1
Fair Value of Financial Instruments - Schedule of Investment Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Total    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance $ 3,998,057 $ 3,851,424
Purchases and other adjustments to cost 239,699 289,661
Sales and repayments (246,248) (321,933)
Transfers in 235 65,828
Transfers out (16,600) (7,980)
Ending balance 3,954,010 3,860,220
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: (22,782) (17,446)
Total | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) (32,673) 3,465
Total | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 11,540 (20,245)
Senior Secured First Lien Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 3,121,003 2,886,706
Purchases and other adjustments to cost 157,762 236,188
Sales and repayments (201,575) (197,648)
Transfers in 235 65,828
Transfers out 0 0
Ending balance 3,051,735 2,985,186
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: (27,410) (7,522)
Senior Secured First Lien Debt | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) (33,943) 3,496
Senior Secured First Lien Debt | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 8,253 (9,384)
Senior Secured Second Lien Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 110,594 103,368
Purchases and other adjustments to cost 51,823 1,889
Sales and repayments (44,652) (2,124)
Transfers in 0 0
Transfers out (16,600) (7,980)
Ending balance 101,855 92,885
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: 761 (1,471)
Senior Secured Second Lien Debt | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 1,270 0
Senior Secured Second Lien Debt | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) (580) (2,268)
Subordinated Debt    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 259,132 196,418
Purchases and other adjustments to cost 28,073 44,823
Sales and repayments (15) (19,704)
Transfers in 0 0
Transfers out 0 0
Ending balance 285,017 220,889
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: (2,173) (648)
Subordinated Debt | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 0 0
Subordinated Debt | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) (2,173) (648)
Collateralized Securities    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 4,861 10,893
Purchases and other adjustments to cost 19 32
Sales and repayments (12) (2,473)
Transfers in 0  
Transfers out 0 0
Ending balance 4,098 7,486
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: (770) (964)
Collateralized Securities | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 0 138
Collateralized Securities | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) (770) (1,104)
Equity/Other    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Beginning balance 502,467 654,039
Purchases and other adjustments to cost 2,022 6,729
Sales and repayments 6 (99,984)
Transfers in 0 0
Transfers out 0 0
Ending balance 511,305 553,774
Net change in unrealized appreciation (depreciation) for the period relating to those Level 3 assets that were still held by the Company at the end of the period: 6,810 (6,841)
Equity/Other | Net realized gain (loss)    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) 0 (169)
Equity/Other | Net change in unrealized appreciation (depreciation) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Net realized gain (loss) $ 6,810 $ (6,841)