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, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 7,176,460	$ 4,274,058	$ 7,099,575	$ 3,096,465
Purchases or originations	382,988	995,734	1,159,199	2,293,820
Repayments / redemptions	(458,687)	(30,579)	(1,099,011)	(41,602)
Sales proceeds	(17,422)	(268,010)	(127,182)	(408,569)
Paid-in-kind interest	15,811	8,200	29,885	13,745
Net change in unrealized gains (losses)	117,267	16,110	138,244	34,624
Net realized gains (losses)	$ 7,214	$ 1,570	$ 7,674	$ 4,412
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	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	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	$ 16,736	$ 4,710	$ 31,983	$ 8,898
Balance, End of Period	7,240,367	5,001,793	7,240,367	5,001,793
First-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	6,686,427	3,979,498	6,728,411	2,848,805
Purchases or originations	382,321	995,734	1,059,498	2,255,540
Repayments / redemptions	(374,771)	(30,579)	(1,015,095)	(41,602)
Sales proceeds	(5,659)	(265,850)	(115,419)	(406,408)
Paid-in-kind interest	10,390	4,306	20,009	6,591
Net change in unrealized gains (losses)	128,445	13,328	134,497	26,783
Net realized gains (losses)	26	1,504	486	4,346
Net amortization of discount on securities	11,530	4,383	26,322	8,269
Balance, End of Period	6,838,709	4,702,324	6,838,709	4,702,324
Second-lien Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	121,036	89,086	93,469	79,091
Purchases or originations			19,198	10,021
Repayments / redemptions	(83,916)		(83,916)
Sales proceeds		(2,160)		(2,161)
Paid-in-kind interest	1,229	494	2,167	494
Net change in unrealized gains (losses)	(11,140)	2,586	(4,055)	2,359
Net realized gains (losses)		66		66
Net amortization of discount on securities	5,056	227	5,402	429
Balance, End of Period	32,265	90,299	32,265	90,299
Mezzanine Debt Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	204,815	111,081	123,184	105,918
Purchases or originations			76,440
Paid-in-kind interest	4,192	3,400	7,709	6,660
Net change in unrealized gains (losses)	935	509	2,500	2,312
Net amortization of discount on securities	150	100	259	200
Balance, End of Period	210,092	115,090	210,092	115,090
Equity and Other Investments
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	164,182	94,393	154,511	62,651
Purchases or originations	667		4,063	28,259
Sales proceeds	(11,763)		(11,763)
Net change in unrealized gains (losses)	(973)	(313)	5,302	3,170
Net realized gains (losses)	7,188		7,188
Balance, End of Period	$ 159,301	$ 94,080	$ 159,301	$ 94,080