Equity Incentive Plans - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jul. 31, 2017	Jan. 31, 2017
Options Outstanding, Number of Shares
Beginning balance (in shares)	56,840,189
Options granted (in shares)	0
Options exercised (in shares)	(2,769,381)
Options forfeited/cancelled (in shares)	(1,266,826)
Ending balance (in shares)	52,803,982	56,840,189
Options Outstanding, Number of Shares, Vested and exercisable (in shares)	31,539,259
Options Outstanding, Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 7.15
Options granted (in dollars per share)	0.00
Options exercised (in dollars per share)	2.53
Options forfeited/cancelled (in dollars per share)	14.04
Ending balance (in dollars per share)	7.23	$ 7.15
Weighted Average Exercise Price, Vested and exercisable (in dollars per share)	$ 4.67
Weighted- Average Remaining Contractual Life
Weighted Average Remaining Contractual Life	6 years 5 months 23 days	7 years
Weighted Average Remaining Contractual Life, Vested and exercisable	5 years 9 months 18 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 315,252	$ 315,502
Aggregate Intrinsic Value, Vested and exercisable	248,932
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost, stock options	$ 98,400
Compensation cost, weighted average term	2 years 6 months
Class A
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Closing price of stock (in dollars per share)	$ 12.07