Net Income per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Numerators:
Net income (in dollars)	$ 7,404	$ 5,594	$ 19,307	$ 14,237
Denominators:
Weighted average common shares outstanding	24,969,800	24,704,814	24,887,304	24,604,981
Dilutive effect of employee stock options and unvested restricted stock (in shares)	627,143	627,908	633,586	717,830
Dilutive effect of stock appreciation rights (in shares)	17,366	25,537	18,609	27,690
Weighted average shares-diluted	25,614,309	25,358,259	25,539,499	25,350,501
Net income per share-basic (in dollars per share)	$ 0.30	$ 0.23	$ 0.78	$ 0.58
Net income per share-diluted (in dollars per share)	$ 0.29	$ 0.22	$ 0.76	$ 0.56
Options excluded from the calculations of diluted earnings per share (in shares)	435,161	677,837	496,686	520,663