Property, Plant and Equipment (Schedule of Property, Plant and Equipment) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 727,513	$ 687,284
Less accumulated depreciation	462,553	421,609
Net property, plant and equipment	264,960	265,675
Depreciation	43,200	44,400
Land
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	20,374	20,859
Buildings
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	109,470	107,659
Machinery and equipment
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	531,838	505,978
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	15,668	15,391
Software
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	25,218	24,464
Construction in progress
Property, Plant and Equipment [Line Items]
Gross property, plant and equipment	$ 24,945	$ 12,933