Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Jan. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 175,302	$ 104,838
Less: accumulated depreciation and amortization	(93,607)	(52,209)
Property and equipment, net	81,695	52,629
Test equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	105,955	65,663
Computer equipment and software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	54,521	31,388
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, gross	4,494	2,852
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 10,332	$ 4,935