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
	Jun. 30, 2014	Jun. 30, 2013
Net loss	$ (13,517)	$ (10,513)
Weighted-average shares of common stock outstanding	79,619	60,463
Weighted-average shares subject to repurchase	(1,931)	(2,163)
Shares used in per-share calculation ― basic	77,688	58,300
Shares used in per-share calculation ― diluted	77,688	58,300
Basic	$ (0.17)	$ (0.18)
Diluted	$ (0.17)	$ (0.18)