Pension and Other Postretirement Benefits - Net Periodic Benefit Cost and Changes in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Domestic [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 298	$ 250	$ 250
Interest Cost	2,114	2,541	2,823
Expected Return on Plan Assets	(3,316)	(3,453)	(3,817)
Settlement Loss	0	0	0
Actuarial Loss Amortization	2,336	2,353	1,757
Prior Service (Credit) Cost Amortization	63	63	63
Net Periodic Benefit Cost	1,495	1,754	1,076
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net (Gain) Loss Arising During The Period	3,576	1,134	7,290
Effect of Plan Amendment	0	0	0
Prior Service (Credit) Cost Amortization	(63)	(63)	(63)
Actuarial Loss	(2,336)	(2,353)	(1,757)
Foreign Currency Exchange Rate Changes	0	0	0
Total Recognized in Other Comprehensive (Income) Loss	1,177	(1,282)	5,470
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	2,672	472	6,546
Foreign [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	2,378	2,799	2,626
Interest Cost	2,314	2,476	3,210
Expected Return on Plan Assets	(2,026)	(2,092)	(2,543)
Settlement Loss	0	170	0
Actuarial Loss Amortization	839	1,136	1,307
Prior Service (Credit) Cost Amortization	(164)	(164)	736
Net Periodic Benefit Cost	3,341	4,325	5,336
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net (Gain) Loss Arising During The Period	2,401	(3,537)	4,973
Effect of Plan Amendment	0	0	242
Prior Service (Credit) Cost Amortization	164	164	(736)
Actuarial Loss	(839)	(1,306)	(1,307)
Foreign Currency Exchange Rate Changes	(1,347)	(2,353)	(3,076)
Total Recognized in Other Comprehensive (Income) Loss	379	(7,032)	96
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	3,720	(2,707)	5,432
Total Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	2,676	3,049	2,876
Interest Cost	4,428	5,017	6,033
Expected Return on Plan Assets	(5,342)	(5,545)	(6,360)
Settlement Loss	0	170	0
Actuarial Loss Amortization	3,175	3,489	3,064
Prior Service (Credit) Cost Amortization	(101)	(101)	799
Net Periodic Benefit Cost	4,836	6,079	6,412
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net (Gain) Loss Arising During The Period	5,977	(2,403)	12,263
Effect of Plan Amendment	0	0	242
Prior Service (Credit) Cost Amortization	101	101	(799)
Actuarial Loss	(3,175)	(3,659)	(3,064)
Foreign Currency Exchange Rate Changes	(1,347)	(2,353)	(3,076)
Total Recognized in Other Comprehensive (Income) Loss	1,556	(8,314)	5,566
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	6,392	(2,235)	11,978
Domestic Other Postretirement Benefits [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	10	17	19
Interest Cost	142	195	232
Actuarial Loss Amortization	0	83	65
Net Periodic Benefit Cost	152	295	316
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net (Gain) Loss Arising During The Period	(401)	(302)	688
Actuarial Loss	0	(83)	(65)
Total Recognized in Other Comprehensive (Income) Loss	(401)	(385)	623
Total Recognized In Net Periodic Benefit Cost And Other Comprehensive Loss Or (Income)	$ (249)	$ (90)	$ 939