Equity Incentive Plans and Employee Stock Purchase Plan - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jul. 31, 2018	Jan. 31, 2018
Shares
Balance - beginning of period (in shares)	12,637,435
Stock options granted (in shares)	0
Stock options exercised (in shares)	(1,191,587)
Stock options forfeited and expired (in shares)	(519,506)
Balance - end of period (in shares)	10,926,342	12,637,435
Vested and exercisable (in shares)	5,948,032	5,540,858
Weighted- Average Exercise Price Per Share
Balance - beginning of period (in dollars per share)	$ 7.63
Stock options granted (in dollars per share)	0.00
Stock options exercised (in dollars per share)	6.78
Stock options forfeited and expired (in dollars per share)	8.25
Balance - end of period (in dollars per share)	7.69	$ 7.63
Vested and exercisable (in dollars per share)	$ 6.62	$ 6.33
Weighted- Average Remaining Contractual Term (In Years)
Balance	7 years 2 months 19 days	7 years 8 months 19 days
Vested and exercisable	6 years 5 months 1 day	6 years 7 months 17 days
Aggregate Intrinsic Value
Balance	$ 507,216	$ 246,227
Vested and exercisable	$ 282,477	$ 115,122