Fair Value of Investments - Changes in Fair Value of Level 3 Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 3,298,961	$ 1,768,188	$ 3,080,569	$ 1,343,705
Purchases and Drawdowns	367,790	601,498	683,023	1,052,342
Sales and Paydowns	(161,034)	(107,724)	(262,572)	(135,489)
Other	7,472	3,973	13,534	7,192
Ending balance	3,512,536	2,266,894	3,512,536	2,266,894
Change in Unrealized Appreciation/(Depreciation) for Level 3 Assets Still Held	(759)	729	(460)	(1,086)
Investments | Realized Gains/ (Losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	2	230	50	230
Investments | Change in Unrealized Appreciation/(Depreciation)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	(655)	729	(2,068)	(1,086)
First lien senior secured debt
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,298,945	1,768,175	3,080,554	1,343,692
Purchases and Drawdowns	367,790	601,498	683,023	1,052,342
Sales and Paydowns	(161,034)	(107,724)	(262,572)	(135,489)
Other	7,472	3,973	13,534	7,191
Ending balance	3,512,520	2,266,885	3,512,520	2,266,885
Change in Unrealized Appreciation/(Depreciation) for Level 3 Assets Still Held	(759)	729	(461)	(1,086)
First lien senior secured debt | Realized Gains/ (Losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	2	230	50	230
First lien senior secured debt | Change in Unrealized Appreciation/(Depreciation)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	(655)	733	(2,069)	(1,081)
Sponsor subordinated note
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	16	13	15	13
Purchases and Drawdowns	0	0	0	0
Sales and Paydowns	0	0	0	0
Other	0	0	0	1
Ending balance	16	9	16	9
Change in Unrealized Appreciation/(Depreciation) for Level 3 Assets Still Held	0	0	1	0
Sponsor subordinated note | Realized Gains/ (Losses)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	0	0	0	0
Sponsor subordinated note | Change in Unrealized Appreciation/(Depreciation)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) included in earnings	$ 0	$ (4)	$ 1	$ (5)