Computation of Net Loss per Common Share - Reconciliation of Numerators and Denominators of EPS Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Numerator:
Net loss	$ (4,737)	$ (15,252)
Denominator:
Weighted-average shares of common stock outstanding (in shares)	20,999	17,089
Weighted-average shares subject to repurchase (in shares)	(832)	(311)
Shares used in per-share calculation ― basic (in shares)	20,167	16,778
Shares used in per-share calculation ― diluted (in shares)	20,167	16,778
Net loss per share ― basic (in dollars per share)	$ (0.23)	$ (0.91)
Net loss per share ― diluted (in dollars per share)	$ (0.23)	$ (0.91)