Computation of Basic and Diluted Net Income Loss Per Share (Detail) (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
Basic Net Income (Loss) Per Share
Net income (loss)	$ 2,684	$ 2,921	$ 11,272	$ (1,072)
Weighted average shares used in computing basic net income (loss) per share	39,417	38,498	39,331	38,221
Net income (loss) per share - basic	$ 0.07	$ 0.08	$ 0.29	$ (0.03)
Diluted Net Income (Loss) Per Share
Net income (loss)	$ 2,684	$ 2,921	$ 11,272	$ (1,072)
Weighted average shares used in computing basic net income (loss) per share	39,417	38,498	39,331	38,221
Effect of dilutive securities	1,448	1,772	2,087
Weighted average shares used in computing diluted net income (loss) per share	40,865	40,270	41,418	38,221
Net income (loss) per share - diluted	$ 0.07	$ 0.07	$ 0.27	$ (0.03)