Fair Value of Financial Instruments - Changes in Fair Value of Investments Using Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 5,001,793	$ 1,758,911	$ 3,096,465	$ 808,801
Purchases or originations	778,777	285,997	3,072,597	1,254,325
Repayments / redemptions	(90,027)	(32,389)	(131,629)	(71,126)
Sales proceeds	(19,862)		(428,430)
Paid-in-kind interest	8,125	4,740	21,870	5,539
Net change in unrealized gains (losses)	56,002	$ 26,032	90,625	$ 40,665
Net realized gains (losses)	$ 130		$ 4,542
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
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	$ 7,798	$ 3,567	$ 16,696	$ 8,654
Balance, End of Period	5,742,736	2,046,858	5,742,736	2,046,858
First-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	4,702,324	1,640,479	2,848,805	800,995
Purchases or originations	778,777	276,420	3,034,317	1,134,872
Repayments / redemptions	(90,027)	(32,389)	(131,629)	(71,126)
Sales proceeds	(19,862)		(426,269)
Paid-in-kind interest	3,925	1,697	10,516	2,496
Net change in unrealized gains (losses)	45,972	25,415	72,753	39,379
Net realized gains (losses)	130		4,477
Net amortization of discount on securities	7,463	3,480	15,732	8,486
Balance, End of Period	5,428,702	1,915,102	5,428,702	1,915,102
Second-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	90,299		79,091
Purchases or originations			10,021
Sales proceeds			(2,161)
Paid-in-kind interest	356		850
Net change in unrealized gains (losses)	2,629		4,989
Net realized gains (losses)			65
Net amortization of discount on securities	235		664
Balance, End of Period	93,519		93,519
Mezzanine Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	115,090	97,750	105,918
Purchases or originations				97,000
Paid-in-kind interest	3,844	3,043	10,504	3,043
Net change in unrealized gains (losses)	259	617	2,571	1,286
Net amortization of discount on securities	100	87	300	168
Balance, End of Period	119,293	101,497	119,293	101,497
Equity and Other Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	94,080	20,682	62,651	7,806
Purchases or originations		9,577	28,259	22,453
Net change in unrealized gains (losses)	7,142		10,312
Balance, End of Period	$ 101,222	$ 30,259	$ 101,222	$ 30,259