Summary of Activity for Nonvested Restricted Shares (Detail) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Nonvested Restricted Stock at Beginning of Year	219,084	258,779	267,090
Number of Shares, Granted	97,257	111,230	113,414
Number of Shares, Vested	(111,695)	(147,678)	(116,507)
Number of Shares, Cancelled	(3,000)	(3,247)	(5,218)
Number of Shares, Nonvested Restricted Stock at End of Year	201,646	219,084	258,779
Weighted Average Grant Date Fair Value, Nonvested Restricted Stock at Beginning of Year	$ 96.54	$ 85.34	$ 62.56
Weighted Average Grant Date Fair Value, Granted	169.62	126.23	139.91
Weighted Average Grant Date Fair Value, Vested	124.78	104.33	87.47
Weighted Average Grant Date Fair Value, Cancelled	30.38	124.82	75.1
Weighted Average Grant Date Fair Value, Nonvested Restricted Stock at End of Year	$ 122.58	$ 96.54	$ 85.34