Balance Sheet Components (Schedule of Property and Equipment, Net) (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Dec. 31, 2017
Total property and equipment, gross	$ 124,202	$ 123,241
Accumulated depreciation and amortization	(104,423)	(102,581)
Total property and equipment, net	19,779	20,660
Computer equipment
Total property and equipment, gross	10,135	10,114
Furniture, fixtures and leasehold improvements
Total property and equipment, gross	21,452	21,640
Software
Total property and equipment, gross	29,193	28,997
Machinery and equipment
Total property and equipment, gross	$ 63,422	$ 62,490