Other Operating Expense, Net (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 24, 2016	Sep. 30, 2017	Sep. 24, 2016
Other operating expense, net:
Loss on property, plant and equipment disposals	$ 0	$ 0	$ 42	$ 259
(Gain) loss on currency exchanges	(66)	88	(65)	85
Amortization of intangibles	76	76	229	229
Retirement expenses	40	27	112	102
Miscellaneous (income) expense	(4)	(50)	(234)	(150)
Other operating expense, net	$ 46	$ 141	$ 84	$ 525