Equity Incentive Plans - Summary of Activity Under the Equity Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Options Outstanding, Number of Shares
Options Outstanding, Number of Shares, Beginning balance (in shares)	68,879,087
Options Outstanding, Number of Shares, Options granted (in shares)	1,999,000
Options Outstanding, Number of Shares, Options exercised (in shares)	(10,180,258)
Options Outstanding, Number of Shares, Options cancelled/forfeited (in shares)	(3,857,640)
Options Outstanding, Number of Shares, Ending balance (in shares)	56,840,189	68,879,087
Options Outstanding, Number of Shares, Vested and exercisable (in shares)	29,575,922
Options Outstanding, Weighted Average Exercise Price
Weighted Average Exercise Price, Beginning balance (in dollars per share)	$ 6.43
Weighted Average Exercise Price, Options granted (in dollars per share)	12.69
Weighted Average Exercise Price, Options exercised (in dollars per share)	1.47
Weighted Average Exercise Price, Options cancelled/forfeited (in dollars per share)	12.18
Weighted Average Exercise Price, Ending balance (in dollars per share)	7.15	$ 6.43
Weighted Average Exercise Price, Vested and exercisable (in dollars per share)	$ 4.12
Options Outstanding, Weighted Average Remaining Contractual Life (Years)
Weighted Average Remaining Contractual Life (Years)	7 years	7 years 10 months 24 days
Weighted Average Remaining Contractual Life (Years), Vested and exercisable	6 years 2 months 12 days
Options Outstanding, Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 315,502	$ 505,131
Aggregate Intrinsic Value, Vested and exercisable	$ 228,436