Convertible Preferred Stock, Stockholders’ Equity (Deficit) and Equity Incentive Plan - Schedule of Stock by Class (Details) - USD ($)	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)	0	158,104,540
Convertible preferred stock, shares issued (in shares)	0	152,665,804
Convertible preferred stock, shares outstanding (in shares)	0	152,665,804	152,665,804	154,031,604
Convertible preferred stock, aggregate liquidation preference		$ 160,724
Series A Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)		67,083,500
Convertible preferred stock, shares issued (in shares)		61,717,700
Convertible preferred stock, shares outstanding (in shares)		61,717,700
Convertible preferred stock, aggregate liquidation preference		$ 9,258
Series B Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)		25,857,784
Convertible preferred stock, shares issued (in shares)		25,857,784
Convertible preferred stock, shares outstanding (in shares)		25,857,784
Convertible preferred stock, aggregate liquidation preference		$ 6,500
Series C Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)		34,363,256
Convertible preferred stock, shares issued (in shares)		34,363,256
Convertible preferred stock, shares outstanding (in shares)		34,363,256
Convertible preferred stock, aggregate liquidation preference		$ 30,000
Series D Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares authorized (in shares)		30,800,000
Convertible preferred stock, shares issued (in shares)		30,727,064
Convertible preferred stock, shares outstanding (in shares)		30,727,064
Convertible preferred stock, aggregate liquidation preference		$ 114,966