Net Loss Per Share - Antidilutive Securities Excluded from Computation of Diluted Net Loss per Common Share of Common Stock Equivalents (Detail) - shares shares in Thousands	6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per common share (in shares)	7,407	5,211
ESPP shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per common share (in shares)	64	55
RSUs and PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per common share (in shares)	4,278	2,296
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted net loss per common share (in shares)	3,065	2,860