Net Loss Per Share - Potentially Dilutive Securities (Details) - shares shares in Thousands	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	14,810	14,201
Shares subject to outstanding common stock options
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	608	353
Shares subject to outstanding RSUs, PSUs and RSAs
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	13,592	13,128
Employee stock purchase plan
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	610	720