Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Cost	$ 2,353,355	$ 2,290,620
Accumulated depreciation	(1,531,766)	(1,471,757)
Total	821,589	818,863
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	58,063	58,407
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	558,264	536,143
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,737,028	$ 1,696,070