Pension and Other Postretirement Benefits - Net Periodic Benefit Cost and Changes in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Domestic [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 383	$ 337	$ 298
Interest Cost	1,847	1,932	2,114
Expected Return on Plan Assets	(2,803)	(3,067)	(3,316)
Settlement Loss	0	1,946	0
Actuarial Loss Amortization	2,276	2,396	2,336
Prior Service (Credit) Cost Amortization	59	63	63
Net Periodic Benefit Cost	1,762	3,607	1,495
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	453	(1,672)	3,576
Prior Service (Credit) Cost Amortization	(59)	(63)	(63)
Actuarial Loss	(2,276)	(4,342)	(2,336)
Foreign Currency Exchange Rate Changes	0	0	0
Total Recognized in Other Comprehensive (Income) Loss	(1,882)	(6,077)	1,177
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	(120)	(2,470)	2,672
Domestic [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	7	8	10
Interest Cost	130	144	142
Actuarial Loss Amortization	42	54	0
Net Periodic Benefit Cost	179	206	152
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	(443)	295	(401)
Actuarial Loss	(42)	(54)	0
Total Recognized in Other Comprehensive (Income) Loss	(485)	241	(401)
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	(306)	447	(249)
Foreign [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	3,426	3,219	2,378
Interest Cost	2,254	2,066	2,314
Expected Return on Plan Assets	(2,228)	(1,994)	(2,026)
Settlement Loss	2	0	0
Actuarial Loss Amortization	881	862	839
Prior Service (Credit) Cost Amortization	(175)	(167)	(164)
Net Periodic Benefit Cost	4,160	3,986	3,341
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	(663)	715	2,401
Prior Service (Credit) Cost Amortization	175	167	164
Actuarial Loss	(883)	(862)	(839)
Foreign Currency Exchange Rate Changes	(890)	2,308	(1,347)
Total Recognized in Other Comprehensive (Income) Loss	(2,261)	2,328	379
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	1,899	6,314	3,720
Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	3,809	3,556	2,676
Interest Cost	4,101	3,998	4,428
Expected Return on Plan Assets	(5,031)	(5,061)	(5,342)
Settlement Loss	2	1,946	0
Actuarial Loss Amortization	3,157	3,258	3,175
Prior Service (Credit) Cost Amortization	(116)	(104)	(101)
Net Periodic Benefit Cost	5,922	7,593	4,836
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	(210)	(957)	5,977
Prior Service (Credit) Cost Amortization	116	104	101
Actuarial Loss	(3,159)	(5,204)	(3,175)
Foreign Currency Exchange Rate Changes	(890)	2,308	(1,347)
Total Recognized in Other Comprehensive (Income) Loss	(4,143)	(3,749)	1,556
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	$ 1,779	$ 3,844	$ 6,392