Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jul. 31, 2016	Jan. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment	$ 152,121	$ 104,838
Less: accumulated depreciation and amortization	(73,598)	(52,209)
Property and equipment, net	78,523	52,629
Test equipment
Property Plant And Equipment [Line Items]
Total property and equipment	94,914	65,663
Computer, equipment and software
Property Plant And Equipment [Line Items]
Total property and equipment	45,340	31,388
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	4,028	2,852
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 7,839	$ 4,935