Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Cost	$ 2,318,542	$ 2,291,188
Accumulated depreciation	(1,490,634)	(1,454,119)
Total	827,908	837,069
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	53,532	55,076
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	535,530	537,474
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,729,480	$ 1,698,638