Fair Value of Financial Instruments - Schedule of Changes in the Fair Value of Investments (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, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	$ 20,601	$ 3,376	$ 32,402	$ 2,539
First-lien senior secured debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	3,531,513	2,167,254	2,898,716	1,758,458
Purchases of investments, net	524,984	402,174	1,319,221	895,464
Payment-in-kind	3,496	5,108	15,235	11,315
Proceeds from investments, net	(5,122)	(22,996)	(192,787)	(57,070)
Net change in unrealized gain (loss) / Net realized gains (losses)	13,085	4,191	26,109	14,293
Net amortization/accretion of premium/discount on investments	5,261	1,350	19,391	3,658
Transfers into (out of) Level 3	2,683	(34,300)	(4,950)	(103,011)
Fair value, end of period	4,070,139	2,522,554	4,070,139	2,522,554
First-lien senior secured debt investments | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	7,322	3,964	15,311	13,742
First-lien senior secured debt investments | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	2	0	2	(2)
Second-lien senior secured debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	158,804	183,925	186,796	184,788
Purchases of investments, net	0	0	0	0
Payment-in-kind	0	0	0	0
Proceeds from investments, net	(17,646)	0	(17,648)	0
Net change in unrealized gain (loss) / Net realized gains (losses)	(72)	2,545	(2,685)	1,393
Net amortization/accretion of premium/discount on investments	210	153	274	442
Transfers into (out of) Level 3	(51,545)	0	(76,986)	0
Fair value, end of period	89,575	186,623	89,575	186,623
Second-lien senior secured debt investments | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	(248)	2,545	(2,861)	1,393
Second-lien senior secured debt investments | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	0	0	0	0
Unsecured debt investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	106,884	48,376	53,368	45,124
Purchases of investments, net	3	0	51,891	0
Payment-in-kind	2,187	1,274	5,450	3,492
Proceeds from investments, net	0	0	0	0
Net change in unrealized gain (loss) / Net realized gains (losses)	2,334	(1,448)	698	(428)
Net amortization/accretion of premium/discount on investments	5	0	6	14
Transfers into (out of) Level 3	0	0	0	0
Fair value, end of period	111,413	48,202	111,413	48,202
Unsecured debt investments | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	2,334	(1,448)	698	(428)
Unsecured debt investments | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	0	0	0	0
Preferred equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	379,430	362,105	370,458	337,069
Purchases of investments, net	13,508	0	20,386	19,664
Payment-in-kind	12,184	1,363	23,781	19,246
Proceeds from investments, net	(100,161)	(20,605)	(102,190)	(22,190)
Net change in unrealized gain (loss) / Net realized gains (losses)	1,684	(2,800)	(3,595)	(14,000)
Net amortization/accretion of premium/discount on investments	2,300	681	2,584	955
Transfers into (out of) Level 3	0	0	0	0
Fair value, end of period	306,747	341,712	306,747	341,712
Preferred equity investments | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	(5,284)	(2,800)	(13,042)	(14,000)
Preferred equity investments | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	4,770	968	4,770	968
Common equity investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	142,366	83,234	108,170	71,541
Purchases of investments, net	7,978	10,015	40,126	21,315
Payment-in-kind	0	0	0	0
Proceeds from investments, net	(3,216)	0	(9,473)	0
Net change in unrealized gain (loss) / Net realized gains (losses)	3,570	888	11,875	1,281
Net amortization/accretion of premium/discount on investments	0	0	0	0
Transfers into (out of) Level 3	0	0	0	0
Fair value, end of period	152,306	94,137	152,306	94,137
Common equity investments | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	5,178	888	13,483	1,281
Common equity investments | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	0	0	0	0
Total
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	4,318,997	2,844,894	3,617,508	2,396,980
Purchases of investments, net	546,473	412,189	1,431,624	936,443
Payment-in-kind	17,867	7,745	44,466	34,053
Proceeds from investments, net	(126,145)	(43,601)	(322,098)	(79,260)
Net amortization/accretion of premium/discount on investments	7,776	2,184	22,255	5,069
Transfers into (out of) Level 3	(48,862)	(34,300)	(81,936)	(103,011)
Fair value, end of period	4,730,180	3,193,228	4,730,180	3,193,228
Total | Net change in unrealized gain (loss)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	9,302	3,149	13,589	1,988
Total | Net realized gains (losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Net change in unrealized gain (loss) / Net realized gains (losses)	$ 4,772	$ 968	$ 4,772	$ 966