Net Income Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Net income (numerator):
Net income	$ 4,577	$ 3,898	$ 12,563	$ 12,665
Shares (denominator):
Weighted average number of common shares outstanding used in basic computation	19,808	20,082	19,963	20,788
Common shares issuable upon the vesting of restricted stock	105	88	104	88
Common shares issuable upon conversion of preferred shares	10	10	10	10
Shares used in diluted computation	19,923	20,180	20,077	20,886
Net income per common share:
Basic (in dollars per share)	$ 0.23	$ 0.19	$ 0.63	$ 0.61
Diluted (in dollars per share)	$ 0.23	$ 0.19	$ 0.63	$ 0.61