Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 179,623		$ 179,623		$ 164,339
Less: Accumulated depreciation and amortization	(73,103)		(73,103)		(59,431)
Property and equipment, net	106,520		106,520		104,908
Depreciation and amortization expense	11,800	$ 9,100	35,400	$ 28,300
Tooling and manufacturing equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	69,889		69,889		66,854
Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	22,756		22,756		20,942
Purchased and internally-developed software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	20,925		20,925		18,112
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 66,053		$ 66,053		$ 58,431