Equity Incentive Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Shares Available for Grant
Balance - beginning of period (in shares)	6,067,076	4,636,564
Authorized (in shares)	2,716,090	2,528,778
Early exercised shares repurchased (in shares)	5,677	35,668
Options forfeited and expired (in shares)	278,650	872,223
Balance - end of period (in shares)	7,026,775	6,067,076	4,636,564
Shares
Balance - beginning of period (in shares)	8,621,010	12,637,435
Options exercised (in shares)	(2,163,361)	(3,144,202)
Options forfeited and expired (in shares)	(278,650)	(872,223)
Balance - end of period (in shares)	6,178,999	8,621,010	12,637,435
Options vested and exercisable (in shares)	4,693,273	5,342,183
Options vested and exercisable - Stock options vested and expected to vest (in shares)	6,178,999
Weighted- Average Exercise Price Per Share
Balance - beginning of period (in dollars per share)	$ 7.75	$ 7.63
Options exercised (in dollars per share)	7.76	7.06
Options forfeited and expired (in dollars per share)	11.28	8.40
Balance - end of period (in dollars per share)	7.60	7.75	$ 7.63
Options vested and exercisable (in dollars per share)	7.08	$ 6.95
Options vested and exercisable - Stock options vested and expected to vest (in dollars per share)	$ 7.60
Weighted- Average Remaining Contractual Term (In Years)
Balance	5 years 8 months 12 days	6 years 8 months 12 days	7 years 8 months 12 days
Options vested and exercisable	5 years 4 months 24 days	6 years
Stock options vested and expected to vest	5 years 8 months 12 days
Aggregate Intrinsic Value
Balance	$ 965,860	$ 729,392	$ 246,227
Options vested and exercisable	736,034	$ 456,275
Stock options vested and expected to vest, intrinsic value	$ 965,860
Restricted Stock Units (RSUs)
Shares Available for Grant
RSUs granted (in shares)	(2,347,359)	(2,134,844)
RSUs forfeited and canceled (in shares)	306,641	128,687