Equity-Based Compensation - Restricted Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Total Unvested
Unvested at beginning of period (in shares)	441,515
Granted (in shares)	80,388
Vested (in shares)	(231,129)
Forfeited (in shares)	(1,917)
Unvested at end of period (in shares)	288,857	441,515
Weighted- Average Grant-Date Fair Value of Award
Unvested at beginning of period (in dollars per share)	$ 36.87
Granted (in dollars per share)	82.97
Vested (in dollars per share)	29.65
Forfeited (in dollars per share)	20.38
Unvested at end of period (in dollars per share)	$ 55.58	$ 36.87
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Weighted- Average Grant-Date Fair Value of Award
Granted (in dollars per share)	$ 82.97	$ 54.71	$ 40.77
Fair value of restricted stock, vested	$ 19,961	$ 18,141	$ 16,601
Total unrecognized compensation expense relating to restricted stock	$ 15,653
Weighted-average amortization period of restricted stock	3 years
Tax benefit recognized from share-based compensation	$ 1,528	$ 1,229	$ 2,537