Computation of Net (Loss) Income Per Common Share - Reconciliation of Numerators and Denominators of EPS Calculation (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Earnings Per Share Reconciliation [Abstract]
Net loss	$ (25,423)	$ (14,623)	$ (38,939)	$ (25,135)
Weighted-average shares of common stock outstanding	83,048	62,787	80,876	61,583
Weighted-average shares subject to repurchase	(1,577)	(1,671)	(1,286)	(1,871)
Shares used in per-share calculation ― basic	81,471	61,116	79,590	59,712
Shares used in per-share calculation ― diluted	81,471	61,116	79,590	59,712
Basic	$ (0.31)	$ (0.24)	$ (0.49)	$ (0.42)
Diluted	$ (0.31)	$ (0.24)	$ (0.49)	$ (0.42)