Net Loss Per Share - Potentially Dilutive Securities (Details) - shares shares in Thousands	9 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	14,822	13,887
Shares subject to outstanding common stock options
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	460	1,114
Shares subject to outstanding RSUs, PSUs and RSAs
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	11,124	12,413
Employee stock purchase plan
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	356	360
Shares underlying the conversion spread in the convertible senior notes
Potentially dilutive securities
Antidilutive securities excluded from computation of earnings per share, amount	2,882	0