Computation of Basic and Diluted Net Income Loss Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic Net Income (Loss) Per Share
Net income (loss)	$ 1,059	$ 5,469	$ (664)	$ 8,588
Weighted average shares used in computing basic net income (loss) per share	39,260	39,431	38,971	39,288
Net income (loss) per share - basic	$ 0.03	$ 0.14	$ (0.02)	$ 0.22
Diluted Net Income (Loss) Per Share
Net income (loss)	$ 1,059	$ 5,469	$ (664)	$ 8,588
Weighted average shares used in computing basic net income (loss) per share	39,260	39,431	38,971	39,288
Effect of dilutive securities	2,077	2,291		2,357
Weighted average shares used in computing diluted net income (loss) per share	41,337	41,722	38,971	41,645
Net income (loss) per share - diluted	$ 0.03	$ 0.13	$ (0.02)	$ 0.21