Accumulated Other Comprehensive Income (AOCI) (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 569,768
Ending balance	605,276
Translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(87,318)	$ (133,298)
Other comprehensive income/(loss) before reclassifications	(23,582)	40,775
Pension/postretirement curtailment gain, net of tax
Interest expense related to swaps reclassified to the Consolidated Statements of Income, net of tax
Pension and postretirement liability adjustments reclassified to Consolidated Statements of Income, net of tax
Net current period other comprehensive income	(23,582)	40,775
Ending balance	(110,900)	(92,523)
Pension and postretirement liability adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(50,536)	(51,719)
Other comprehensive income/(loss) before reclassifications	2,389	(1,427)
Pension/postretirement curtailment gain, net of tax	(525)
Interest expense related to swaps reclassified to the Consolidated Statements of Income, net of tax
Pension and postretirement liability adjustments reclassified to Consolidated Statements of Income, net of tax	379	498
Net current period other comprehensive income	2,243	(929)
Ending balance	(48,293)	(52,648)
Derivative valuation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	1,953	828
Other comprehensive income/(loss) before reclassifications	7,374	(679)
Pension/postretirement curtailment gain, net of tax
Interest expense related to swaps reclassified to the Consolidated Statements of Income, net of tax	105	768
Pension and postretirement liability adjustments reclassified to Consolidated Statements of Income, net of tax
Net current period other comprehensive income	7,479	89
Ending balance	9,432	917
Total Other Comprehensive Income [Member] [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(135,901)	(184,189)
Other comprehensive income/(loss) before reclassifications	(13,819)	38,669
Pension/postretirement curtailment gain, net of tax	(525)
Interest expense related to swaps reclassified to the Consolidated Statements of Income, net of tax	105	768
Pension and postretirement liability adjustments reclassified to Consolidated Statements of Income, net of tax	379	498
Net current period other comprehensive income	(13,860)	39,935
Ending balance	$ (149,761)	$ (144,254)