Net Loss per Share Attributable to Common Stockholders - Summary of Weighted Average Outstanding Shares Excluded from Computation of Diluted Net Loss per Share (Details) - shares shares in Thousands	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	28,497	101,459	90,002
Redeemable convertible preferred stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		79,519	71,465
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	16,654	18,146	17,036
Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	7,233	2,994	1
Warrants to purchase redeemable convertible
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		86	736
Repurchasable shares from early-exercised options and unvested restricted stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	551	623	764
Contingently issuable common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	115	91
Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	3,944