Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Cost	$ 2,391,611		$ 2,391,611		$ 2,374,407
Accumulated depreciation	(1,538,027)		(1,538,027)		(1,520,138)
Total	853,584		853,584		854,269
Depreciation expense	44,501	$ 38,408	89,530	$ 78,616
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	56,104		56,104		55,567
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	555,345		555,345		546,809
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,780,162		$ 1,780,162		$ 1,772,031