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	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Numerator:
Net loss	$ (43,433)	$ (144,348)	$ (134,612)	[1]
Denominator:
Weighted-average number of shares outstanding—basic and diluted	155,849	147,762	141,351	[1]
Net loss per share—basic and diluted	$ (0.28)	$ (0.98)	$ (0.95)	[1]
Class A Common Stock
Numerator:
Net loss	$ (43,433)	$ (144,348)	$ (131,089)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	155,849	147,762	137,652
Net loss per share—basic and diluted	$ (0.28)	$ (0.98)	$ (0.95)
Class B Common Stock
Numerator:
Net loss			$ (3,523)
Denominator:
Weighted-average number of shares outstanding—basic and diluted			3,699
Net loss per share—basic and diluted			$ (0.95)

[1] As reported and disclosed under ASC Topic 840