CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total	Comprehensive Income [Member]
Balance at Mar. 31, 2009	$ 117,846	$ 9,046	$ 0	$ 126,892	$ 0
Balance (in shares) at Mar. 31, 2009	21,933,000
Increase (Decrease) in Stockholders' Equity
Common stock issued under stock option exercises	915	0	0	915	0
Common stock issued under stock option exercises (in shares)	128,000
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes	(446)	0	0	(446)	0
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes (in shares)	51,000
Share-based compensation	5,398	0	0	5,398	0
Excess tax benefits from share-based awards and other tax adjustments	1,337	0	0	1,337	0
Warrants issued for intangible assets				0
Components of comprehensive income:
Net income	0	13,023	0	13,023	13,023
Change in unrealized gain (loss) on investments, net of tax	0	0	0	0	0
Comprehensive income	0	0	0	0	13,023
Balance at Mar. 31, 2010	125,050	22,069	0	147,119	0
Balance (in shares) at Mar. 31, 2010	22,112,000
Increase (Decrease) in Stockholders' Equity
Common stock issued under stock option exercises	1,684	0	0	1,684	0
Common stock issued under stock option exercises (in shares)	314,000
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes	(2,013)	0	0	(2,013)	0
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes (in shares)	161,000
Share-based compensation	4,857	0	0	4,857	0
Excess tax benefits from share-based awards and other tax adjustments	2,215	0	0	2,215	0
Warrants issued for intangible assets	249	0	0	249	0
Components of comprehensive income:
Net income	0	14,537	0	14,537	14,537
Change in unrealized gain (loss) on investments, net of tax	0	0	0	0	0
Comprehensive income	0	0	0	0	14,537
Balance at Mar. 31, 2011	132,042	36,606	0	168,648	0
Balance (in shares) at Mar. 31, 2011	22,587,000
Increase (Decrease) in Stockholders' Equity
Common stock issued under stock option exercises	615	0	0	615	0
Common stock issued under stock option exercises (in shares)	122,000
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes	(2,211)	0	0	(2,211)	0
Common stock issued in settlement of restricted stock units, net of shares withheld for employee taxes (in shares)	158,000
Repurchases of common stock, net	(27,328)	0	0	(27,328)	0
Repurchases of common stock, net (in shares)	(1,168,000)
Share-based compensation	5,715	0	0	5,715	0
Excess tax benefits from share-based awards and other tax adjustments	842	0	0	842	0
Warrants issued for intangible assets	388	0	0	388	0
Components of comprehensive income:
Net income	0	13,091	0	13,091	13,091
Change in unrealized gain (loss) on investments, net of tax	0	0	25	25	25
Comprehensive income	0	0	0	0	13,116
Balance at Mar. 31, 2012	$ 110,063	$ 49,697	$ 25	$ 159,785
Balance (in shares) at Mar. 31, 2012	21,699,000