Net Loss per Share - Summary of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2020	Jul. 31, 2019
Numerator:
Net loss	$ (7,656)	$ (25,550)	$ (36,234)	$ (36,828)	$ (33,206)	$ (73,062)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	154,732		147,032		153,353	146,205
Net loss per share—basic and diluted	$ (0.05)		$ (0.25)		$ (0.22)	$ (0.50)