Summary of Significant Accounting Policies (Schedule of Accumulated Other Comprehensive Income (loss)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of Goods and Services Sold	$ 849,756	$ 767,550	$ 659,867
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(176,669)	(183,234)
Other comprehensive income (loss) before reclassifications	(14,858)	(304)
Amounts reclassified from accumulated other comprehensive income (loss)	11,540	6,869
Other comprehensive income (loss)	(3,318)	6,565	25,485
Ending balance	(179,987)	(176,669)	(183,234)
Foreign currency translation adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(86,178)	(93,970)
Other comprehensive income (loss) before reclassifications	(10,762)	7,792
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Other comprehensive income (loss)	(10,762)	7,792
Ending balance	(96,940)	(86,178)	(93,970)
Gain (loss) on derivative financial instruments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	459	863
Other comprehensive income (loss) before reclassifications	(2,978)	538
Amounts reclassified from accumulated other comprehensive income (loss)	918	(942)
Other comprehensive income (loss)	(2,060)	(404)
Ending balance	(1,601)	459	863
Pension and other post-retirement benefit adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(90,950)	(90,127)
Other comprehensive income (loss) before reclassifications	(1,118)	(8,634)
Amounts reclassified from accumulated other comprehensive income (loss)	10,622	7,811
Other comprehensive income (loss)	9,504	(823)
Ending balance	(81,446)	(90,950)	(90,127)
Foreign Currency Forward Contracts [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Gain (loss) on derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Cost of Goods and Services Sold	$ (62)	$ (62)	$ 62