Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Jan. 31, 2017
Property Plant And Equipment [Line Items]
Total property and equipment	$ 41,079	$ 32,573
Less accumulated depreciation and amortization	(28,833)	(22,163)
Total property and equipment, net	12,246	10,410
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	20,176	17,431
Sales Demonstration Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	7,656	5,903
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	6,010	5,941
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	2,046	1,550
Beta Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	1,706	1,060
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	$ 2,825	$ 39