Equity Incentive Plans - Summary of Activity Under the Equity Incentive Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Options Outstanding, Number of Shares
Options Outstanding, Number of Shares, Beginning Balance	54,284,474
Options Outstanding, Number of Shares, Options granted	19,269,524
Options Outstanding, Number of Shares, Options exercised	(2,313,598)
Options Outstanding, Number of Shares, Options cancelled	(2,361,313)
Options Outstanding, Number of Shares, Ending Balance	68,879,087	54,284,474
Options Outstanding, Number of Shares, Vested and exercisable	24,297,716
Options Outstanding, Number of Shares, Vested and expected to vest	66,945,857
Options Outstanding, Weighted Average Exercise Price
Weighted Average Exercise Price, Beginning Balance	$ 3.02
Weighted Average Exercise Price, Options granted	15.76
Weighted Average Exercise Price, Options exercised	2.58
Weighted Average Exercise Price, Options Cancelled	7.96
Weighted Average Exercise Price, Ending Balance	6.43	$ 3.02
Weighted Average Exercise Price, Vested and exercisable	2.04
Weighted Average Exercise Price, Vested and expected to vest	$ 6.37
Options Outstanding, Weighted Average Remaining Contractual Life (Years)
Weighted Average Remaining Contractual Life (Years)	7 years 10 months 24 days	8 years 3 months 18 days
Weighted Average Remaining Contractual Life (Years), Vested and exercisable	6 years 8 months 12 days
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	7 years 10 months 24 days
Options Outstanding, Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 505,131	$ 523,654
Aggregate Intrinsic Value, Vested and exercisable	267,213
Aggregate Intrinsic Value, Vested and expected to vest	$ 494,544