Pensions and Other Postretirement Benefit Plans (Schedule of Plan Benefit Obligations) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
United States [Member]
Weighted average assumptions used to determine benefit obligations, end of year:
Discount rate	3.70%	4.20%
Compensation increase
Non-U.S. Pension Plans [Member]
Weighted average assumptions used to determine benefit obligations, end of year:
Discount rate	2.83%	2.98%
Compensation increase	3.02%	3.29%
United States Postretirement Benefits Plan [Member]
Weighted average assumptions used to determine benefit obligations, end of year:
Discount rate	3.59%	4.00%
Compensation increase
Non-U.S. Postretirement Benefits Plan [Member]
Weighted average assumptions used to determine benefit obligations, end of year:
Discount rate	3.40%	3.70%
Compensation increase	3.00%	3.00%
Pension Plans [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	$ 210,856	$ 199,856
Service cost	2,720	2,656	$ 2,959
Interest cost	7,476	7,885	7,787
Plan participants' contributions	211	249
Actuarial (gain)/loss	6,626	17,676
Benefits paid	(7,697)	(7,057)
Settlements and curtailments	(8)	(2,436)
Plan amendments and other	(3)	36
Foreign currency changes	10,730	(8,009)
Benefit obligation, end of year	230,911	210,856	199,856
Accumulated benefit obligation	220,622	200,790
Other postretirement benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	57,488	59,970
Service cost	244	254	330
Interest cost	2,214	2,443	2,437
Plan participants' contributions		72
Actuarial (gain)/loss	2,743	(395)
Benefits paid	(4,230)	(4,884)
Settlements and curtailments
Plan amendments and other
Foreign currency changes		28
Benefit obligation, end of year	58,531	57,488	$ 59,970
Accumulated benefit obligation