Fair Value of Financial Instruments - Changes in Fair Value of Investments Using Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 7,099,575	$ 3,096,465
Purchases or originations	776,210	1,298,086
Repayments / redemptions	(640,324)	(11,023)
Sales proceeds	(109,761)	(140,558)
Paid-in-kind interest	14,076	5,545
Net change in unrealized gains (losses)	20,978	18,515
Net realized gains (losses)	$ 460	$ 2,842
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
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	$ 15,246	$ 4,186
Balance, End of Period	7,176,460	4,274,058
First-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	6,728,411	2,848,805
Purchases or originations	677,175	1,259,806
Repayments / redemptions	(640,324)	(11,023)
Sales proceeds	(109,761)	(140,558)
Paid-in-kind interest	9,621	2,285
Net change in unrealized gains (losses)	6,053	13,456
Net realized gains (losses)	460	2,842
Net amortization of discount on securities	14,792	3,885
Balance, End of Period	6,686,427	3,979,498
Second-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	93,469	79,091
Purchases or originations	19,198	10,021
Paid-in-kind interest	938
Net change in unrealized gains (losses)	7,086	(227)
Net amortization of discount on securities	345	201
Balance, End of Period	121,036	89,086
Mezzanine Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	123,184	105,918
Purchases or originations	76,440
Paid-in-kind interest	3,517	3,260
Net change in unrealized gains (losses)	1,565	1,803
Net amortization of discount on securities	109	100
Balance, End of Period	204,815	111,081
Equity and Other Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	154,511	62,651
Purchases or originations	3,397	28,259
Net change in unrealized gains (losses)	6,274	3,483
Balance, End of Period	$ 164,182	$ 94,393