Weighted Average Shares and Net Income Per Share - Calculations of Basic and Diluted Weighted Average Common Shares (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Income	$ 23,398,000	$ 19,898,000	$ 44,975,000	$ 39,703,000
Basic:
Weighted average common shares outstanding	17,133,000	17,123,000	17,127,000	17,133,000
Net Income per share	$ 1.37	$ 1.16	$ 2.63	$ 2.32
Diluted:
Weighted average common shares outstanding	17,341,000	17,346,000	17,327,000	17,365,000
Treasury stock impact of stock options	208,000	223,000	200,000	232,000
Total common and common equivalent shares	17,341,000	17,346,000	17,327,000	17,365,000
Net Income per share	$ 1.35	$ 1.15	$ 2.6	$ 2.29