Net Increase in Net Assets Resulting from Operations per Common Share - Computation of Basic Income Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Income (Loss)	$ 44,341	$ 32,250	$ 45,619
Weighted-average shares outstanding for the period
Basic	40,509,269	40,971,242	34,183,358	27,617,425	18,701,021	9,300,960	2,795,274	10,774
Diluted	40,509,269	40,971,242	34,183,358
Basic and diluted income per common share
Basic	$ 1.09	$ 0.79	$ 1.33
Diluted	$ 1.09	$ 0.79	$ 1.33