Employee Incentive Plans - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Apr. 30, 2017	Jan. 31, 2017	Apr. 30, 2017
Number of Options
Number of options, outstanding beginning of period (in shares)	32,866,862
Number of options, granted (in shares)	2,596,568
Number of options, exercised (in shares)	(1,022,650)
Number of options, canceled (in shares)	(501,308)
Number of options, outstanding end of period (in shares)	33,939,472	32,866,862
Vested and exercisable, number of options (in shares)			12,656,317
Weighted- Average Exercise Price
Options outstanding, weighted average exercise price beginning of period (in dollars per share)	$ 6.01
Options granted, weighted average exercise price (in dollars per share)	11.03
Options exercised, weighted average exercise price (in dollars per share)	2.75
Options canceled, weighted average exercise price (in dollars per share)	7.53
Options outstanding, weighted average exercise price end of period (in dollars per share)	$ 6.47	$ 6.01
Vested and exercisable, weighted average exercise price (in dollars per share)			$ 3.57
Additional Disclosures
Options outstanding, weighted average remaining contractual term	8 years 1 month 13 days	8 years 2 months 16 days
Vested and exercisable, weighted average remaining contractual term	6 years 9 months 18 days
Options outstanding beginning of period, aggregate intrinsic value	$ 664,506	$ 145,570	$ 664,506
Options outstanding end of period, aggregate intrinsic value	$ 664,506	$ 145,570
Vested and exercisable, aggregate intrinsic value			$ 284,473