Equity Incentive Plans - Summary of Stock-Based Compensation Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 150,673	$ 116,668	$ 58,225
Cost of revenue—product
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	1,630	601	276
Cost of revenue—support
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	9,050	5,639	2,388
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	71,229	63,495	31,135
Sales and marketing
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	47,687	34,317	16,966
General and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 21,077	$ 12,616	$ 7,460