Investments - Investment Portfolio Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Total
Fair value, beginning of period	$ 2,361,224	$ 2,054,120
New investments	1,226,467	670,674
Investment restructuring	(3,705)
Transfers into (out of) Level 3, net	(9,417)	(5,910)
Proceeds from sales of investments / return of capital	(95,448)	(215,027)
Loan origination fees received	(19,206)	(13,245)
Principal repayments received	(568,983)	(181,758)
Fair value, end of period	2,888,065	2,361,224
Payment in kind interest /dividends
Total
Realized gain (loss)	$ 25,044	$ 17,715
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Accretion of loan premium / discount
Total
Realized gain (loss)	$ 1,024	$ 1,076
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 15,549	$ 10,279
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Realized gain (loss)
Total
Realized gain (loss)	$ (23,024)	$ (1,548)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ (21,460)	$ 24,848
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Senior debt and 1st lien notes
Total
Fair value, beginning of period	$ 1,915,633	$ 1,736,050
New investments	1,161,149	517,892
Investment restructuring	(25,679)
Transfers into (out of) Level 3, net	(357)	0
Proceeds from sales of investments / return of capital	(94,669)	(213,277)
Loan origination fees received	(18,626)	(13,171)
Principal repayments received	(515,854)	(140,893)
Fair value, end of period	2,402,177	1,915,633
Senior debt and 1st lien notes | Payment in kind interest /dividends
Total
Realized gain (loss)	$ 7,313	$ 5,815
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Senior debt and 1st lien notes | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 986	$ 692
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Senior debt and 1st lien notes | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 14,507	$ 9,821
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Senior debt and 1st lien notes | Realized gain (loss)
Total
Realized gain (loss)	$ (14,579)	$ (2,157)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Senior debt and 1st lien notes | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ (27,647)	$ 14,861
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Subordinated debt and 2nd lien notes
Total
Fair value, beginning of period	$ 130,273	$ 143,294
New investments	34,579	34,390
Investment restructuring	8,861
Transfers into (out of) Level 3, net	(9,060)	(6,432)
Proceeds from sales of investments / return of capital	0	0
Loan origination fees received	(580)	(74)
Principal repayments received	(51,701)	(39,437)
Fair value, end of period	110,909	130,273
Subordinated debt and 2nd lien notes | Payment in kind interest /dividends
Total
Realized gain (loss)	$ 4,571	$ 2,952
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Subordinated debt and 2nd lien notes | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 38	$ 384
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Subordinated debt and 2nd lien notes | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 1,042	$ 458
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Subordinated debt and 2nd lien notes | Realized gain (loss)
Total
Realized gain (loss)	$ (8,485)	$ (278)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Subordinated debt and 2nd lien notes | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ 1,371	$ (4,984)
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Structured Product
Total
Fair value, beginning of period	$ 15,705	$ 16,380
New investments	4,000	0
Investment restructuring	0
Transfers into (out of) Level 3, net	0	0
Proceeds from sales of investments / return of capital	0	0
Loan origination fees received	0	0
Principal repayments received	(1,428)	(1,428)
Fair value, end of period	19,899	15,705
Structured Product | Payment in kind interest /dividends
Total
Realized gain (loss)		$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Structured Product | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Structured Product | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Structured Product | Realized gain (loss)
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Structured Product | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ 1,622	$ 753
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Equity shares
Total
Fair value, beginning of period	$ 297,138	$ 157,313
New investments	17,061	118,392
Investment restructuring	13,113
Transfers into (out of) Level 3, net	0	522
Proceeds from sales of investments / return of capital	(167)	(1,750)
Loan origination fees received	0	0
Principal repayments received	0	0
Fair value, end of period	337,684	297,138
Equity shares | Payment in kind interest /dividends
Total
Realized gain (loss)	$ 13,160	$ 8,948
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Equity shares | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Equity shares | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Equity shares | Realized gain (loss)
Total
Realized gain (loss)	$ 40	$ 887
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Equity shares | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ (2,661)	$ 12,826
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Equity warrants
Total
Fair value, beginning of period	$ 2,475	$ 1,083
New investments	0	0
Investment restructuring	0
Transfers into (out of) Level 3, net	0	0
Proceeds from sales of investments / return of capital	0	0
Loan origination fees received	0	0
Principal repayments received	0	0
Fair value, end of period	2,813	2,475
Equity warrants | Payment in kind interest /dividends
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income	Total payment-in-kind interest income
Equity warrants | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Equity warrants | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees	Interest and other financing fees
Equity warrants | Realized gain (loss)
Total
Realized gain (loss)	$ 0	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments	Net realized gains (losses) on investments
Equity warrants | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ 338	$ 1,392
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments	Net realized gains (losses) on investments
Royalty rights
Total
Fair value, beginning of period	$ 0
New investments	9,678
Investment restructuring	0
Transfers into (out of) Level 3, net	0
Proceeds from sales of investments / return of capital	(612)
Loan origination fees received	0
Principal repayments received	0
Fair value, end of period	14,583	$ 0
Royalty rights | Payment in kind interest /dividends
Total
Realized gain (loss)	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total payment-in-kind interest income
Royalty rights | Accretion of loan premium / discount
Total
Realized gain (loss)	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees
Royalty rights | Accretion of deferred loan origination revenue
Total
Realized gain (loss)	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Interest and other financing fees
Royalty rights | Realized gain (loss)
Total
Realized gain (loss)	$ 0
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net realized gains (losses) on investments
Royalty rights | Unrealized appreciation (depreciation)
Total
Realized gain (loss)	$ 5,517
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net unrealized appreciation (depreciation) on investments