Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Cost	$ 2,157,935		$ 2,138,950
Accumulated depreciation	(1,360,253)		(1,332,453)
Total	797,682		806,497
Depreciation expense	32,188	$ 32,164
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	49,834		53,623
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	518,238		529,982
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,589,863		$ 1,555,345