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, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	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	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Investment Income	$ 119,542	$ 114,435	$ 107,605	$ 96,505	$ 100,149	$ 77,839	$ 63,888	$ 67,429	$ 78,323	$ 71,200	$ 62,828	$ 66,242	$ 438,087	$ 309,305	$ 278,593
Net Expenses	64,269	63,980	57,919	53,155	47,536	40,659	23,066	31,717	32,132	34,730	35,440	33,932	239,323	140,356	135,850
Net investment income	54,684	49,994	48,784	42,937	52,613	37,180	40,822	35,712	46,191	36,470	27,388	32,310	196,399	166,327	142,359
Total unrealized and realized gains (losses)	(3,523)	14,826	4,306	10,015	(6,351)	(2,749)	(54,347)	5,173	(4,373)	18,486	30,966	24,342	25,624	(58,274)	69,421
Increase in Net Assets Resulting from Operations	$ 51,161	$ 64,820	$ 53,090	$ 52,952	$ 46,262	$ 34,431	$ (13,525)	$ 40,885	$ 41,818	$ 54,956	$ 58,354	$ 56,652	$ 222,023	$ 108,053	$ 211,780
Net Asset Value per Share as of the End of the Quarter	$ 17.04	$ 16.97	$ 16.74	$ 16.59	$ 16.48	$ 16.36	$ 16.27	$ 16.88	$ 16.84	$ 17.18	$ 16.85	$ 16.47	$ 17.04	$ 16.48	$ 16.84	$ 17.16	$ 16.83	$ 16.25	$ 16.09	$ 15.95	$ 15.15	$ 15.53	$ 15.52