Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance	$ (8,393)	$ (12,162)
Unrealized losses	(832)	322
Amounts reclassified from accumulated other comprehensive income (loss)	198	253
Tax effect	(52)	(96)
Net of tax amount	(686)	479
Ending balance	(9,079)	(11,683)
Foreign currency translation adjustments [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance	(3,305)	(5,500)
Unrealized losses	(832)	322
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Tax effect	0	0
Net of tax amount	(832)	322
Ending balance	(4,137)	(5,178)
Defined benefit pension plans [member]
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance	(5,088)	(6,662)
Unrealized losses	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	198	253
Tax effect	(52)	(96)
Net of tax amount	146	157
Ending balance	$ (4,942)	$ (6,505)