Goodwill And Other Intangible Assets (Details of Amortizable Intangible Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Amortization Of Intangible Assets [Line Items]
Total gross amortizable intangible assets	$ 236,627	$ 234,796
Total accumulated amortization	(66,444)	(64,437)
Amortizable intangible assets, net	170,183	170,359
Patents [Member]
Amortization Of Intangible Assets [Line Items]
Total gross amortizable intangible assets	5,610	5,279
Total accumulated amortization	(5,566)	(5,226)
Land Rights [Member]
Amortization Of Intangible Assets [Line Items]
Total gross amortizable intangible assets	5,061	4,947
Total accumulated amortization	(2,957)	(2,883)
Technology/Know-how And Other [Member]
Amortization Of Intangible Assets [Line Items]
Total gross amortizable intangible assets	129,984	131,070
Total accumulated amortization	(45,048)	(45,214)
Customer Relationships [Member]
Amortization Of Intangible Assets [Line Items]
Total gross amortizable intangible assets	95,972	93,500
Total accumulated amortization	$ (12,873)	$ (11,114)