Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Apr. 30, 2016	Jan. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 133,413	$ 104,838
Less: accumulated depreciation and amortization	(62,158)	(52,209)
Property and equipment, net	71,255	52,629
Test Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	83,384	65,663
Computer, Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	40,442	31,388
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, gross	3,532	2,852
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 6,055	$ 4,935