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		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net income (numerator):
Net income (in dollars)	$ 4,502	$ 2,732	$ 10,259	$ 7,705
Shares (denominator):
Weighted average number of common shares outstanding used in basic computation	20,126	20,016	20,100	19,988
Common shares issuable upon vesting of restricted stock	110	120	112	121
Common shares issuable upon conversion of preferred shares	10	10	10	10
Shares used in diluted computation	20,246	20,146	20,222	20,119
Net income per common share:
Basic (in dollars per share)	$ 0.22	$ 0.14	$ 0.51	$ 0.39
Diluted (in dollars per share)	$ 0.22	$ 0.14	$ 0.51	$ 0.38