Pensions and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Defined Benefit Pension Plan [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	371	411	1,113	1,232
Expected return on plan assets	0	0	0	0
Amortization of prior service cost (credit)	36	36	108	108
Amortization of losses (gains)	159	82	477	247
Curtailments and settlements	0	0	0	0
Net periodic benefit cost	566	529	1,698	1,587
Defined Benefit Pension Plan [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	900	948	2,775	2,776
Interest cost	1,175	1,247	3,628	3,613
Expected return on plan assets	(463)	(519)	(1,430)	(1,543)
Amortization of prior service cost (credit)	52	19	161	55
Amortization of losses (gains)	1,520	1,595	4,690	4,596
Curtailments and settlements	441	331	1,358	983
Net periodic benefit cost	3,625	3,621	11,182	10,480
Other Postretirement Benefits [Member] | Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	35	33	103	99
Interest cost	69	77	205	232
Amortization of prior service cost (credit)	(37)	(209)	(111)	(627)
Amortization of losses (gains)	(10)	(24)	(29)	(70)
Net periodic benefit cost	57	(123)	168	(366)
Other Postretirement Benefits [Member] | Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net service cost	71	71	219	202
Interest cost	28	26	86	76
Amortization of prior service cost (credit)	0	0	0	0
Amortization of losses (gains)	26	16	80	45
Net periodic benefit cost	$ 125	$ 113	$ 385	$ 323