Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance			$ (12,162)	$ (13,394)
Unrealized gains	$ 881	$ 245	1,203	1,997
Amounts reclassified from accumulated other comprehensive income (loss)			506	829
Tax effect			(192)	(321)
Net of tax amount			1,517	2,505
Ending balance	(10,645)	(10,889)	(10,645)	(10,889)
Foreign currency translation adjustments [Member]
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance			(5,500)	(6,244)
Unrealized gains			1,203	1,997
Amounts reclassified from accumulated other comprehensive income (loss)			0	0
Tax effect			0	0
Net of tax amount			1,203	1,997
Ending balance	(4,297)	(4,247)	(4,297)	(4,247)
Defined benefit pension plans [member]
Accumulated other comprehensive income (loss) [Roll Forward]
Beginning balance			(6,662)	(7,150)
Unrealized gains			0	0
Amounts reclassified from accumulated other comprehensive income (loss)			506	829
Tax effect			(192)	(321)
Net of tax amount			314	508
Ending balance	$ (6,348)	$ (6,642)	$ (6,348)	$ (6,642)