Summary of Activity for Nonvested Restricted Shares (Detail) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Nonvested at Beginning of Year	267,090	233,120	300,115
Number of Shares, Granted	113,414	179,377	118,292
Number of Shares, Vested	(116,507)	(136,280)	(169,347)
Number of Shares, Cancelled	(5,218)	(9,127)	(15,940)
Number of Shares, Nonvested at End of Year	258,779	267,090	233,120
Weighted Average Grant Date Fair Value, Nonvested at Beginning of Year	$ 62.56	$ 75.35	$ 78.94
Weighted Average Grant Date Fair Value, Granted	139.91	63.83	90.08
Weighted Average Grant Date Fair Value, Vested	87.47	78.89	92.98
Weighted Average Grant Date Fair Value, Cancelled	75.10	71.46	58.64
Weighted Average Grant Date Fair Value, Nonvested at End of Year	$ 102.45	$ 62.56	$ 75.35