Net Income Per Share - Reconciliation of the numerators and denominators of the basic and diluted net income per share computations (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income (numerator):
Net income	$ 2,732	$ 4,150	$ 7,705	$ 8,905
Shares (denominator):
Weighted average number of common shares outstanding used in basic computation	20,016	19,902	19,988	19,875
Common shares issuable upon vesting of restricted stock	120	132	121	139
Common shares issuable upon conversion of preferred shares	10	10	10	10
Shares used in diluted computation	20,146	20,044	20,119	20,024
Net income per common share:
Basic (in dollars per share)	$ 0.14	$ 0.21	$ 0.39	$ 0.45
Diluted (in dollars per share)	$ 0.14	$ 0.21	$ 0.38	$ 0.44