Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Defined Benefit Pension Plan [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	$ 0	$ 0
Interest cost	371	410
Expected return on plan assets	0	0
Amortization of prior service cost (credit)	36	36
Amortization of losses (gains)	159	82
Curtailments and settlements	0	0
Net periodic benefit cost	566	528
Defined Benefit Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	948	903
Interest cost	1,242	1,167
Expected return on plan assets	(488)	(506)
Amortization of prior service cost (credit)	55	18
Amortization of losses (gains)	1,604	1,478
Curtailments and settlements	462	322
Net periodic benefit cost	3,823	3,382
Other Postretirement Benefits [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	34	33
Interest cost	68	77
Amortization of prior service cost (credit)	(37)	(209)
Amortization of losses (gains)	(10)	(23)
Net periodic benefit cost	55	(122)
Other Postretirement Benefits [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	75	64
Interest cost	30	24
Amortization of prior service cost (credit)	0	0
Amortization of losses (gains)	27	14
Net periodic benefit cost	$ 132	$ 102