Accumulated Other Comprehensive Income (AOCI) (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 569,768
Ending balance	591,994
Translation adjustments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(87,318)	$ (133,298)
Other comprehensive income/(loss) before reclassifications	17,646	10,126
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
Net current period other comprehensive income	17,646	10,126
Ending balance	(69,672)	(123,172)
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	(141)	(193)
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	128	164
Net current period other comprehensive income	(13)	(29)
Ending balance	(50,549)	(51,748)
Derivative valuation adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	1,953	828
Other comprehensive income/(loss) before reclassifications	4,343	258
Interest expense related to swaps reclassified to the Statement of Income, net of tax	137	372
Pension and postretirement liability adjustments reclassified to Statement of Income, net of tax
Net current period other comprehensive income	4,480	630
Ending balance	6,433	1,458
Total Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(135,901)	(184,189)
Other comprehensive income/(loss) before reclassifications	21,848	10,191
Interest expense related to swaps reclassified to the Statement of Income, net of tax	137	372
Pension and postretirement liability adjustments reclassified to Statement of Income, net of tax	128	164
Net current period other comprehensive income	22,113	10,727
Ending balance	$ (113,788)	$ (173,462)