Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Oct. 31, 2016	Jan. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment	$ 167,700	$ 104,838
Less: accumulated depreciation and amortization	(85,612)	(52,209)
Property and equipment, net	82,088	52,629
Test equipment
Property Plant And Equipment [Line Items]
Total property and equipment	103,491	65,663
Computer, equipment and software
Property Plant And Equipment [Line Items]
Total property and equipment	50,235	31,388
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	4,072	2,852
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 9,902	$ 4,935