Common Stock - Schedule of Total Stock-Based Compensation Expense Recognized by Type of Award (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Stock-based compensation:
Total stock-based compensation expense	$ 51,818	$ 13,834	$ 9,755
Stock Options
Stock-based compensation:
Total stock-based compensation expense	19,821	13,834	9,755
RSUs
Stock-based compensation:
Total stock-based compensation expense	30,984
ESPP
Stock-based compensation:
Total stock-based compensation expense	1,013
Cost of Product Revenue
Stock-based compensation:
Total stock-based compensation expense	1,612	264	181
Cost of Support and Maintenance Revenue
Stock-based compensation:
Total stock-based compensation expense	1,579	323	176
Research and development
Stock-based compensation:
Total stock-based compensation expense	21,608	5,227	2,906
Sales and marketing
Stock-based compensation:
Total stock-based compensation expense	10,432	4,115	3,073
General and administrative
Stock-based compensation:
Total stock-based compensation expense	$ 16,587	$ 3,905	$ 3,419