Accumulated Other Comprehensive Income (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (184,189)	$ (158,844)	$ (107,767)
Other comprehensive income/(loss) before reclassifications	44,363	(23,163)	(53,013)
Pension/postretirement settlements and curtailments		45	103
Pension/postretirement plan remeasurement	2,037	(4,394)	(622)
Interest expense related to swaps reclassified to the Statement of Income, net of tax	924	1,488	1,233
Pension and postretirement liability adjustments reclassified to Statement of Income, net of tax	964	679	1,222
Net current period other comprehensive income	48,288	(25,345)	(51,077)
Ending balance	(135,901)	(184,189)	(158,844)
Translation Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(133,298)	(108,655)	(55,240)
Other comprehensive income/(loss) before reclassifications	45,980	(24,643)	(53,415)
Pension/postretirement settlements and curtailments
Pension/Postretirement plan change in benefits
Pension/postretirement plan remeasurement
Interest expense related to swaps reclassified to the Statement of Income, net of tax
Net current period other comprehensive income	45,980	(24,643)	(53,415)
Ending balance	(87,318)	(133,298)	(108,655)
Pension and Postretirement Liability Adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(51,719)	(48,725)	(51,666)
Other comprehensive income/(loss) before reclassifications	(1,818)	676	2,238
Pension/postretirement settlements and curtailments	2,037	45	103
Pension/postretirement plan remeasurement		(4,394)	(622)
Interest expense related to swaps reclassified to the Statement of Income, net of tax
Pension and postretirement liability adjustments reclassified to Statement of Income, net of tax	964	679	1,222
Net current period other comprehensive income	1,183	(2,994)	2,941
Ending balance	(50,536)	(51,719)	(48,725)
Derivative Valuation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	828	(1,464)	(861)
Other comprehensive income/(loss) before reclassifications	201	804	(1,836)
Pension/postretirement settlements and curtailments
Pension/postretirement plan remeasurement
Interest expense related to swaps reclassified to the Statement of Income, net of tax	924	1,488	1,233
Pension and postretirement liability adjustments reclassified to Statement of Income, net of tax
Net current period other comprehensive income	1,125	2,292	(603)
Ending balance	$ 1,953	$ 828	$ (1,464)