Earnings Per Share - Schedule of Computation of Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												9 Months Ended		12 Months Ended
	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, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Basic Earnings Per Share
Net increase (decrease) in net assets resulting from operations	$ 1,288	$ 15,993	$ 5,659	$ 4,239	$ 20,540	$ 25,441	$ 32,144	$ 42,411	$ 33,166	$ 33,289	$ 2,995	$ (147,247)	$ 22,940	$ 78,125	$ 82,364	$ 111,861
Weighted average shares outstanding													64,585,966		64,516,533	65,259,176	67,228,771	70,645,944
Earnings (Loss) Per Share — Basic													$ 0.36	$ 1.21	$ 1.28	$ 1.71