Stock Option Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019
Options Outstanding
Balance at the beginning of the period (in shares)	19,117,696
Exercised (in shares)	(4,395,673)
Canceled (in shares)	(1,191,660)
Balance at the end of the period (in shares)	13,530,363	19,117,696
Exercisable (in shares)	13,478,227
Vested and expected to vest (in shares)	13,530,363
Weighted- Average Exercise Price
Balance at the beginning of the period (in dollars per share)	$ 5.83
Exercised (in dollars per share)	2.88
Canceled (in dollars per share)	15.25
Balance at the end of the period (in dollars per share)	5.96	$ 5.83
Exercisable (in dollars per share)	5.91
Vested and expected to vest (in dollars per share)	$ 5.96
Weighted-Average Remaining Contractual Term (Years)
Balance	2 years 1 month 6 days	4 years 3 months 18 days
Vested and Expected to Vest — January 31, 2020	2 years 1 month 6 days
Exercisable— January 31, 2020	2 years
Aggregate Intrinsic Value (in thousands)
Balance	$ 70,057	$ 154,431
Exercisable— January 31, 2020	70,057
Vested and Expected to Vest — January 31, 2020	$ 70,057