Net Income Per Share - Reconciliation of the numerators and denominators of the basic and diluted net income per share computations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Net income (numerator):
Net income (in dollars)	$ 6,594	$ 5,757
Shares (denominator)
Weighted average number of common shares outstanding used in basic computation	20,181	20,074
Common shares issuable upon vesting of restricted stock	142	114
Common shares issuable upon conversion of preferred shares	10	10
Shares used in diluted computation	20,333	20,198
Net income per common share:
Basic (in dollars per share)	$ 0.33	$ 0.29
Diluted (in dollars per share)	$ 0.32	$ 0.29