v3.25.2
Investments - Rollforward of Level 3 Investments Measured at Fair Value (Details) - USD ($)
$ in Thousands
 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Fair value, beginning balance $ 675,633 $ 800,775
Funding and purchases of investments, at cost 109,257 52,118
Principal payments and sale proceeds received from investments (86,260) (136,589)
Transfers between investment types 0 0
Gross transfers out of Level 3 0 (73)
Fair value, ending balance 717,321 713,243
Net change in unrealized gains (losses) on Level 3 investments held $ 1,616 $ 4,488
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income Flag Net change in unrealized gains (losses) on investments Net change in unrealized gains (losses) on investments
Net amortization and accretion of premiums and discounts and end-of-term payments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 5,728 $ 2,589
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income Flag Interest expense and amortization of fees Interest expense and amortization of fees
Net realized gains (losses) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 2,278 $ (29,651)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income Flag Net realized gains (losses) on investments Net realized gains (losses) on investments
Net change in unrealized gains (losses) included in earnings    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 1,678 $ 16,465
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income Flag Net change in unrealized gains (losses) on investments Net change in unrealized gains (losses) on investments
Payment-in-kind coupon    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 9,007 $ 7,609
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income Flag Payment-in-kind interest income Payment-in-kind interest income
Debt investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Fair value, beginning balance $ 560,105 $ 730,295
Funding and purchases of investments, at cost 105,514 50,882
Principal payments and sale proceeds received from investments (83,952) (135,700)
Transfers between investment types 0 (8,028)
Gross transfers out of Level 3 0 0
Fair value, ending balance 590,565 615,656
Net change in unrealized gains (losses) on Level 3 investments held (5,664) (13,700)
Debt investments | Net amortization and accretion of premiums and discounts and end-of-term payments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 5,728 2,589
Debt investments | Net realized gains (losses) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 (29,228)
Debt investments | Net change in unrealized gains (losses) included in earnings    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings (5,837) (2,763)
Debt investments | Payment-in-kind coupon    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 9,007 7,609
Warrant investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Fair value, beginning balance 39,963 30,055
Funding and purchases of investments, at cost 1,760 436
Principal payments and sale proceeds received from investments 0 (889)
Transfers between investment types (339) (384)
Gross transfers out of Level 3 0 0
Fair value, ending balance 43,924 36,561
Net change in unrealized gains (losses) on Level 3 investments held 2,306 6,726
Warrant investments | Net amortization and accretion of premiums and discounts and end-of-term payments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 0
Warrant investments | Net realized gains (losses) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 (423)
Warrant investments | Net change in unrealized gains (losses) included in earnings    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 2,540 7,766
Warrant investments | Payment-in-kind coupon    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 0
Equity investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Fair value, beginning balance 75,565 40,425
Funding and purchases of investments, at cost 1,983 800
Principal payments and sale proceeds received from investments (2,308) 0
Transfers between investment types 339 8,412
Gross transfers out of Level 3 0 (73)
Fair value, ending balance 82,832 61,026
Net change in unrealized gains (losses) on Level 3 investments held 4,974 11,462
Equity investments | Net amortization and accretion of premiums and discounts and end-of-term payments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 0 0
Equity investments | Net realized gains (losses) on investments    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 2,278 0
Equity investments | Net change in unrealized gains (losses) included in earnings    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings 4,975 11,462
Equity investments | Payment-in-kind coupon    
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]    
Gain (loss) included in earnings $ 0 $ 0