Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Oct. 31, 2017	Jan. 31, 2017
Property Plant And Equipment [Line Items]
Total property and equipment	$ 37,407	$ 32,573
Less accumulated depreciation and amortization	(27,184)	(22,163)
Total property and equipment, net	10,223	10,410
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	19,902	17,431
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	5,944	5,941
Sales Demonstration Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	7,350	5,903
Beta Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	1,639	1,060
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	1,777	1,550
Software
Property Plant And Equipment [Line Items]
Total property and equipment	660	649
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 135	$ 39