Weighted Average Shares and Net Income Per Share - Calculations of Basic and Diluted Weighted Shares (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Earnings Per Share [Abstract]
Net Income	$ 8,267,000	$ 7,883,000	$ 15,167,000	$ 16,182,000
Basic:
Weighted average common shares outstanding	19,902,000	20,819,000	20,026,000	20,877,000
Net Income per share, Basic	$ 0.42	$ 0.38	$ 0.76	$ 0.78
Diluted:
Weighted average common shares outstanding	19,902,000	20,819,000	20,026,000	20,877,000
Treasury stock impact of stock options	161,000	231,000	173,000	253,000
Total common and common equivalent shares	20,063,000	21,050,000	20,199,000	21,130,000
Net Income per share, Diluted	$ 0.41	$ 0.37	$ 0.75	$ 0.77