Equity Incentive Plans - Early Exercise of Stock Options (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)	2,163,361	3,144,202
Common stock subject to repurchase (in shares)	14,332	59,356
Fair value of shares subject to repurchase	$ 0.1	$ 0.5
Early Exercised Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock (in shares)	1,064	6,059
Stock repurchased (in shares)	5,677	35,668