Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 169,860		$ 164,339
Less: Accumulated depreciation and amortization	(65,330)		(59,431)
Property and equipment, net	104,530		104,908
Depreciation and amortization expense	10,500	$ 9,100
Tooling and manufacturing equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	65,202		66,854
Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	22,327		20,942
Purchased and internally-developed software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	18,957		18,112
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 63,374		$ 58,431