Fair Value of Financial Instruments - Changes in Fair Value of Investments Using Level 3 Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 3,096,465	$ 808,801
Purchases or originations	1,298,086	444,761
Repayments / redemptions	(11,023)	(6,286)
Sales proceeds	(140,558)
Paid-in-kind interest	5,545	21
Net change in unrealized gains (losses)	18,515	$ 13,761
Net realized gains (losses)	$ 2,842
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
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 amortization of discount on securities	$ 4,186	$ 1,394
Balance, End of Period	4,274,058	1,262,452
First-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	2,848,805	800,995
Purchases or originations	1,259,806	436,123
Repayments / redemptions	(11,023)	(6,286)
Sales proceeds	(140,558)
Paid-in-kind interest	2,285	21
Net change in unrealized gains (losses)	13,456	13,761
Net realized gains (losses)	2,842
Net amortization of discount on securities	3,885	1,394
Balance, End of Period	3,979,498	1,246,008
Second-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	79,091
Purchases or originations	10,021
Net change in unrealized gains (losses)	(227)
Net amortization of discount on securities	201
Balance, End of Period	89,086
Mezzanine Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	105,918
Paid-in-kind interest	3,260
Net change in unrealized gains (losses)	1,803
Net amortization of discount on securities	100
Balance, End of Period	111,081
Equity and Other Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	62,651	7,806
Purchases or originations	28,259	8,638
Net change in unrealized gains (losses)	3,483
Balance, End of Period	$ 94,393	$ 16,444