Financial Statement Components - Components of Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	9 Months Ended
	Sep. 29, 2018 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	$ 262,383
Ending Balance Value	294,075
Foreign Currency Translations [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(1,647)
Current period change	(530)
Ending Balance Value	(2,177)
Defined Benefit Pension Plans [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(387)
Ending Balance Value	(387)
Unrealized Income (Loss) on Investment [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(90)
Current period change	7
Ending Balance Value	(83)
Accumulated Other Comprehensive Income (Loss) [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance Value	(2,124)
Current period change	(523)
Ending Balance Value	$ (2,647)