Weighted Average Shares and Net Income Per Share - Calculations of Basic and Diluted Weighted Average Shares (Detail) - USD ($)	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net Income	$ 8,775,000	$ 7,491,000
Basic:
Weighted average common shares outstanding	18,811,000	19,572,000
Net Income per share	$ 0.47	$ 0.38
Diluted:
Weighted average common shares outstanding	18,811,000	19,572,000
Treasury stock impact of stock options	189,000	182,000
Total common and common equivalent shares	19,000,000	19,754,000
Net Income per share	$ 0.46	$ 0.38