Balance Sheet Components - Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 29, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 145,133	$ 143,845
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(119,502)	(114,580)
Property, Plant and Equipment, Net	25,631	29,265
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	88,129	87,121
Software and Software Development Costs [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	35,527	35,139
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	14,978	15,051
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 6,499	$ 6,534