Pension and Other Postretirement Benefits - Net Periodic Benefit Cost and Changes in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 3,941	$ 3,809
Interest Cost	6,359	4,101
Domestic plan [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	434	383	$ 337
Interest Cost	3,313	1,847	1,932
Expected Return on Plan Assets	(3,227)	(2,803)	(3,067)
Settlement Loss	0	0	1,946
Actuarial Loss Amortization	2,348	2,276	2,396
Prior Service (Credit) Cost Amortization	0	59	63
Net Periodic Benefit Cost	2,869	1,762	3,607
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	3,926	(453)	(1,672)
Prior service credit (cost)	0	(59)	(63)
Actuarial Loss	(2,347)	(2,276)	(4,342)
Foreign Currency Exchange Rate Changes	0	0	0
Total Recognized in Other Comprehensive (Income) Loss	1,579	(1,882)	(6,077)
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	4,448	(120)	(2,470)
Domestic plan [Member] | Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	6	7	8
Interest Cost	143	130	144
Prior Service (Credit) Cost Amortization	0	42	54
Net Periodic Benefit Cost	149	179	206
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	395	(443)	295
Actuarial Loss	0	(42)	(54)
Total Recognized in Other Comprehensive (Income) Loss	395	(485)	241
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	544	(306)	447
Foreign [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	3,507	3,426	3,219
Interest Cost	3,046	2,254	2,066
Expected Return on Plan Assets	(3,668)	(2,228)	(1,994)
Settlement Loss	258	2	0
Actuarial Loss Amortization	757	881	862
Prior Service (Credit) Cost Amortization	(165)	(175)	(167)
Net Periodic Benefit Cost	3,735	4,160	3,986
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	3,826	(663)	715
Prior service credit (cost)	196	175	167
Actuarial Loss	(1,015)	(883)	(862)
Foreign Currency Exchange Rate Changes	(61)	(890)	2,308
Total Recognized in Other Comprehensive (Income) Loss	2,946	(2,261)	2,328
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	6,681	1,899	6,314
Pension Plans, Defined Benefit [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	3,941	3,809	3,556
Interest Cost	6,359	4,101	3,998
Expected Return on Plan Assets	(6,895)	(5,031)	(5,061)
Settlement Loss	258	2	1,946
Actuarial Loss Amortization	3,105	3,157	3,258
Prior Service (Credit) Cost Amortization	(165)	(116)	(104)
Net Periodic Benefit Cost	6,603	5,922	7,593
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net Loss (Gain) Arising During The Period	7,752	(210)	(957)
Prior service credit (cost)	196	116	104
Actuarial Loss	(3,362)	(3,159)	(5,204)
Foreign Currency Exchange Rate Changes	(61)	(890)	2,308
Total Recognized in Other Comprehensive (Income) Loss	4,525	(4,143)	(3,749)
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	$ 11,128	$ 1,779	$ 3,844