Accumulated Other Comprehensive Income (AOCI) (Schedule of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 702,689	$ 608,280	$ 573,015
Ending balance	819,865	702,689	608,280
Translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(122,852)	(115,976)	(87,318)
Other comprehensive income/(loss) before reclassifications	39,649	(6,876)	(28,658)
Pension/postretirement settlements and curtailments	0	0	0
Pension/postretirement plan remeasurement	0	0	0
Interest expense related to swaps reclassified to the Statements of Income, net of tax	0	0	0
Pension and postretirement liability adjustments reclassified to Statements of Income, net of tax	0	0	0
Adjustment related to prior period change in opening valuation allowance		0
Net current period other comprehensive income	39,649	(6,876)	(28,658)
Ending balance	(83,203)	(122,852)	(115,976)
Pension and postretirement liability adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(49,994)	(47,109)	(50,536)
Other comprehensive income/(loss) before reclassifications	(722)	(525)	1,275
Pension/postretirement settlements and curtailments	283	376	1,146
Pension/postretirement plan remeasurement	10,390	(1,437)	443
Interest expense related to swaps reclassified to the Statements of Income, net of tax	0	0	0
Pension and postretirement liability adjustments reclassified to Statements of Income, net of tax	382	47	563
Adjustment related to prior period change in opening valuation allowance		(1,346)
Net current period other comprehensive income	10,333	(2,885)	3,427
Ending balance	(39,661)	(49,994)	(47,109)
Derivative valuation adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,135)	4,697	1,953
Other comprehensive income/(loss) before reclassifications	(9,363)	(10,523)	2,853
Pension/postretirement settlements and curtailments	0	0	0
Pension/postretirement plan remeasurement	0	0	0
Interest expense related to swaps reclassified to the Statements of Income, net of tax	2,954	2,691	(109)
Pension and postretirement liability adjustments reclassified to Statements of Income, net of tax	0	0	0
Adjustment related to prior period change in opening valuation allowance		0
Net current period other comprehensive income	(6,409)	(7,832)	2,744
Ending balance	(9,544)	(3,135)	4,697
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(175,981)	(158,388)	(135,901)
Other comprehensive income/(loss) before reclassifications	29,564	(17,924)	(24,530)
Pension/postretirement settlements and curtailments	283	376	1,146
Pension/postretirement plan remeasurement	10,390	(1,437)	443
Interest expense related to swaps reclassified to the Statements of Income, net of tax	2,954	2,691	(109)
Pension and postretirement liability adjustments reclassified to Statements of Income, net of tax	382	47	563
Adjustment related to prior period change in opening valuation allowance		(1,346)
Net current period other comprehensive income	43,573	(17,593)	(22,487)
Ending balance	$ (132,408)	$ (175,981)	$ (158,388)