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, 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, 2023	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Basic Earnings Per Share
Net increase (decrease) in net assets resulting from operations	$ 33,262	$ 29,963	$ 25,404	$ 30,132	$ 1,288	$ 15,993	$ 5,659	$ 4,239	$ 20,540	$ 25,441	$ 32,144	$ 42,411	$ 88,628	$ 22,940	$ 118,760	$ 82,364
Weighted average shares outstanding														64,585,966	65,330,350	64,516,533	65,259,176	67,228,771
Basic earnings (loss) per share													$ 1.36	$ 0.36	$ 1.82	$ 1.28