v3.26.1
Fair Value of Financial Instruments - Changes in Fair Value of Investments Using Level 3 Inputs (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period $ 3,181,834 $ 3,485,041
Purchases or originations 162,769 174,590
Repayments / redemptions (116,146) (287,890)
Sales Proceeds 10 (1,557)
Paid-in-kind interest 6,676 5,233
Net change in unrealized gains (losses) $ (18,644) $ (10,792)
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Unrealized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction, Operating, after Tax Unrealized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction, Operating, after Tax
Net realized gains (losses) $ (42,739) $ 399
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Realized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction, Operating, after Tax Realized Gain (Loss), Investment, Derivative, and Foreign Currency Transaction, Operating, after Tax
Net amortization of discount on securities $ 4,376 $ 6,205
Transfers into (out of) Level 3 (282)  
Balance, End of Period 3,177,854 3,371,229
First-lien Debt Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period 2,956,297 3,287,829
Purchases or originations 148,095 143,772
Repayments / redemptions (116,146) (287,890)
Sales Proceeds 10  
Paid-in-kind interest 3,873 3,292
Net change in unrealized gains (losses) (53,390) (8,324)
Net realized gains (losses) 5 24
Net amortization of discount on securities 4,221 6,095
Balance, End of Period 2,942,965 3,144,798
Second-lien Debt Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period 30,456 18,535
Purchases or originations   15,357
Paid-in-kind interest 1,136 805
Net change in unrealized gains (losses) 38,849 (2,486)
Net realized gains (losses) (39,489)  
Net amortization of discount on securities 121 89
Balance, End of Period 31,073 32,300
Mezzanine Debt Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period 61,684 39,091
Purchases or originations   12,740
Paid-in-kind interest 1,667 1,055
Net change in unrealized gains (losses) 367 (728)
Net amortization of discount on securities 34 21
Balance, End of Period 63,752 52,179
Equity and Other Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period   139,586
Purchases or originations   2,721
Sales Proceeds   (1,557)
Paid-in-kind interest   81
Net change in unrealized gains (losses)   746
Net realized gains (losses)   375
Balance, End of Period   $ 141,952
Equity and Structured Credit Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Balance, beginning of period 133,397  
Purchases or originations 9  
Net change in unrealized gains (losses) (4,470)  
Net realized gains (losses) (3,255)  
Transfers into (out of) Level 3 (282)  
Balance, End of Period 125,399  
Joint Venture Investments    
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]    
Purchases or originations 14,665  
Balance, End of Period $ 14,665