Selected Quarterly Financial Data (Unaudited) - Schedule of Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Investment Income	$ 123,704	$ 119,223	$ 121,816	$ 117,783	$ 119,542	$ 114,435	$ 107,605	$ 96,505	$ 100,149	$ 77,839	$ 63,888	$ 67,429	$ 482,526	$ 438,087	$ 309,305
Net Expenses	64,949	63,599	65,446	64,571	64,269	63,980	57,919	53,155	47,536	40,659	23,066	31,717	258,565	239,323	140,356
Net investment income	57,585	54,926	55,144	52,362	54,684	49,994	48,784	42,937	52,613	37,180	40,822	35,712	220,017	196,399	166,327
Total unrealized and realized gains (losses)	(6,594)	(14,271)	(7,742)	(4,844)	(3,523)	14,826	4,306	10,015	(6,351)	(2,749)	(54,347)	5,173	(33,451)	25,624	(58,274)
Increase in net assets resulting from operations	$ 50,992	$ 40,655	$ 47,401	$ 47,518	$ 51,161	$ 64,820	$ 53,090	$ 52,952	$ 46,262	$ 34,431	$ (13,525)	$ 40,885	$ 186,566	$ 222,023	$ 108,053
Net Asset Value per Share as of the End of the Quarter	$ 17.16	$ 17.12	$ 17.19	$ 17.17	$ 17.04	$ 16.97	$ 16.74	$ 16.59	$ 16.48	$ 16.36	$ 16.27	$ 16.88	$ 17.16	$ 17.04	$ 16.48	$ 16.84	$ 17.16	$ 16.83	$ 16.25	$ 16.09	$ 15.95	$ 15.15	$ 15.53