Financial Statement Components - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	$ 262,383
Current period change	1,898	$ 1,936
Ending Balance Value	260,727
Foreign Currency Translations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(1,647)
Current period change	1,987
Ending Balance Value	340
Defined Benefit Pension Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(387)
Ending Balance Value	(387)
Unrealized (Loss) on Investment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(90)
Current period change	(89)
Ending Balance Value	(179)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(2,124)
Ending Balance Value	$ (226)