Weighted Average Shares and Net Income Per Share - Calculations of Basic and Diluted Weighted Average Shares (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income	$ 7,049,000	$ 6,691,000	$ 21,492,000	$ 21,859,000
Basic:
Weighted average common shares outstanding	19,426,000	19,673,000	19,526,000	19,908,000
Net Income per share	$ 0.36	$ 0.34	$ 1.10	$ 1.10
Diluted:
Weighted average common shares outstanding	19,426,000	19,673,000	19,526,000	19,908,000
Treasury stock impact of stock options	123,000	179,000	153,000	175,000
Total common and common equivalent shares	19,549,000	19,852,000	19,679,000	20,083,000
Net Income per share	$ 0.36	$ 0.34	$ 1.09	$ 1.09