Stock-Based Compensation - Summary of Stock Option Activity Under Equity Incentive Plans and Related Information (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Shares Subject to Options Outstanding, Beginning balance	12,318,800	15,634,518
Shares Subject to Options Outstanding, Options granted	1,533,056	1,018,136
Shares Subject to Options Outstanding, Options exercised	(2,098,726)	(2,908,077)
Shares Subject to Options Outstanding, Options forfeited/cancelled	(910,010)	(1,425,777)
Shares Subject to Options Outstanding, Ending balance	10,843,120	12,318,800	15,634,518
Shares Subject to Options Outstanding, Vested and expected to vest	10,750,742
Shares Subject to Options Outstanding, Exercisable	8,703,037
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted Average Exercise Price, Beginning Balance	$ 7.44	$ 6.92
Weighted Average Exercise Price, Options granted	17.46	13.88
Weighted Average Exercise Price, Options exercised	6.94	3.81
Weighted Average Exercise Price, Options forfeited/cancelled	15.03	13.68
Weighted Average Exercise Price, Ending Balance	8.32	$ 7.44	$ 6.92
Weighted Average Exercise Price, Vested and expected to vest	8.26
Weighted Average Exercise Price, Exercisable	$ 6.46
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Weighted Average Remaining Contractual Life (Years)	5 years 8 months 26 days	6 years 5 months 1 day	7 years 1 month 13 days
Weighted Average Remaining Contractual Life (Years), Vested and expected to vest	5 years 8 months 15 days
Weighted Average Remaining Contractual Life (Years), Exercisable	5 years 25 days
Aggregate Intrinsic Value, Balance	$ 150,922	$ 119,606	$ 82,541
Aggregate Intrinsic Value, Vested and expected to vest	150,334
Aggregate Intrinsic Value, Exercisable	$ 137,306