CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data	Common Stock	Additional Paid-In Capital	Accumulated other Comprehensive Income (Loss)	Accumulated Deficit	Total
Beginning balance, amount at Mar. 31, 2012	$ 71	$ 241,555	$ (58)	$ (123,118)	$ 118,450
Beginning balance, shares at Mar. 31, 2012	70,679,493
Issuance of common stock under stock plans	1	2,400	0	0	2,401
Issuance of common stock under stock plans, shares	1,503,238
Cost of issuance of common stock	0	(43)	0	0	(43)
Repurchase of common stock	0	(419)	0	0	(419)
Repurchase of common stock, shares	(73,751)
Stock-based compensation expense	0	2,634	0	0	2,634
Income tax benefit from stock-based compensation	0	49	0	0	49
Unrealized investment gain (loss)	0	0	22	0	22
Foreign currency translation adjustment					0
Net income	0	0	0	13,939	13,939
Ending balance, amount at Mar. 31, 2013	72	246,176	(36)	(109,179)	137,033
Ending balance, shares at Mar. 31, 2013	72,108,980
Issuance of common stock under stock plans	2	5,165	0	0	5,167
Issuance of common stock under stock plans, shares	2,091,435
Issuance of common stock, net of issuance costs	14	125,736	0	0	125,750
Issuance of common stock, net of issuance costs, shares	14,375,000
Repurchase of common stock	0	(489)	0	0	(489)
Repurchase of common stock, shares	(50,400)
Stock-based compensation expense	0	7,595	0	0	7,595
Income tax benefit from stock-based compensation	0	142	0	0	142
Unrealized investment gain (loss)	0	0	(41)	0	(41)
Foreign currency translation adjustment	0	0	507	0	507
Net income	0	0	0	2,514	2,514
Ending balance, amount at Mar. 31, 2014	88	384,325	430	(106,665)	278,178
Ending balance, shares at Mar. 31, 2014	88,525,015
Issuance of common stock under stock plans	2	4,525	0	0	4,527
Issuance of common stock under stock plans, shares	2,043,781
Cost of issuance of common stock	0	(8)	0	0	(8)
Repurchase of common stock	(2)	(19,369)	0	0	(19,371)
Repurchase of common stock, shares	(2,503,268)
Stock-based compensation expense	0	9,347	0	0	9,347
Income tax benefit from stock-based compensation	0	151	0	0	151
Unrealized investment gain (loss)	0	0	(26)	0	(26)
Foreign currency translation adjustment	0	0	(2,513)	0	(2,513)
Net income	0	0	0	1,926	1,926
Ending balance, amount at Mar. 31, 2015	$ 88	$ 378,971	$ (2,109)	$ (104,739)	$ 272,211
Ending balance, shares at Mar. 31, 2015	88,065,528