Fair Value of Financial Instruments - Changes in Fair Value of Investments Using Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 3,330,769	$ 2,821,516	$ 3,208,957	$ 2,693,938
Purchases or originations	246,613	279,221	456,183	454,175
Repayments / redemptions	(284,273)	(119,056)	(371,622)	(5,809)
Sale Proceeds	(9,109)	(554)	(9,109)	(176,394)
Paid-in-kind interest	9,181	3,335	16,291	6,634
Net change in unrealized gains (losses)	$ (4,519)	$ 4,171	$ (14,942)	$ 8,180
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net Change In Unrealized Gains Losses On Investments And Foreign Currency Translation	Net Change In Unrealized Gains Losses On Investments And Foreign Currency Translation	Net Change In Unrealized Gains Losses On Investments And Foreign Currency Translation	Net Change In Unrealized Gains Losses On Investments And Foreign Currency Translation
Net realized gains (losses)	$ (1,772)	$ 349	$ (2,391)	$ 5,048
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Net Realized Gains Losses on Investments and Foreign Currency Translation	Net Realized Gains Losses on Investments and Foreign Currency Translation	Net Realized Gains Losses on Investments and Foreign Currency Translation	Net Realized Gains Losses on Investments and Foreign Currency Translation
Net amortization of discount on securities	$ 6,451	$ 3,808	$ 9,974	$ 7,018
Transfers into (out of) Level 3		731		731
Balance, End of Period	3,293,341	2,993,521	3,293,341	2,993,521
First-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	3,114,679	2,628,849	2,993,786	2,495,959
Purchases or originations	246,590	249,417	450,028	417,459
Repayments / redemptions	(282,738)	(119,056)	(370,087)
Sale Proceeds	(9,109)		(9,109)	(176,394)
Paid-in-kind interest	7,656	3,081	13,387	6,297
Net change in unrealized gains (losses)	(6,705)	11,366	(10,482)	27,147
Net realized gains (losses)	(1,772)	(25)	(2,391)	(25)
Net amortization of discount on securities	6,393	3,758	9,862	6,947
Balance, End of Period	3,074,994	2,777,390	3,074,994	2,777,390
Second-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	28,669	44,805	35,975	40,762
Purchases or originations	0		2,004	4,850
Repayments / redemptions	(1,535)		(1,535)
Paid-in-kind interest	338	194	569	194
Net change in unrealized gains (losses)	481	(5,315)	(9,093)	(6,142)
Net amortization of discount on securities	40	24	73	44
Balance, End of Period	27,993	39,708	27,993	39,708
Mezzanine Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	40,077	11,093	38,865	10,158
Purchases or originations		29,111	0	29,806
Paid-in-kind interest	1,111	60	2,178	143
Net change in unrealized gains (losses)	1,076	(53)	1,200	103
Net amortization of discount on securities	18	26	39	27
Balance, End of Period	42,282	40,237	42,282	40,237
Equity and Other Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	147,344	136,769	140,331	147,059
Purchases or originations	23	693	4,151	2,060
Repayments / redemptions			0	(5,809)
Sale Proceeds		(554)
Paid-in-kind interest	76		157
Net change in unrealized gains (losses)	629	(1,827)	3,433	(12,928)
Net realized gains (losses)		374	0	5,073
Transfers into (out of) Level 3		731		731
Balance, End of Period	$ 148,072	$ 136,186	$ 148,072	$ 136,186