Equity Incentive Plans - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 31, 2017	Jan. 31, 2017
Options Outstanding, Number of Shares
Beginning balance (in shares)	56,840,189
Options granted (in shares)	1,000,000
Options exercised (in shares)	(5,502,179)
Options forfeited/cancelled (in shares)	(2,362,891)
Ending balance (in shares)	49,975,119	56,840,189
Options Outstanding, Number of Shares, Vested and exercisable (in shares)	30,500,061
Options Outstanding, Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.15
Options granted (in dollars per share)	14.92
Options exercised (in dollars per share)	2.86
Options forfeited/cancelled (in dollars per share)	14.41
Ending balance (in dollars per share)	7.43	$ 7.15
Weighted Average Exercise Price, Vested and exercisable (in dollars per share)	$ 4.84
Weighted- Average Remaining Contractual Life
Weighted Average Remaining Contractual Life	6 years 4 months 24 days	7 years
Weighted Average Remaining Contractual Life, Vested and exercisable	5 years 10 months 24 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 457,252	$ 315,502
Aggregate Intrinsic Value, Vested and exercisable	$ 355,871
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average fair value of the options granted (in dollars per share)	$ 5.58
Unrecognized compensation cost, stock options	$ 89,300
Compensation cost, weighted average term	2 years 8 months 12 days
Class A
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Closing price of stock (in dollars per share)	$ 16.43