Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Cost	$ 2,291,188	$ 2,169,290
Accumulated depreciation	(1,454,119)	(1,381,441)
Total	837,069	787,849
Land [Member]
Property, Plant and Equipment [Line Items]
Cost	55,076	56,118
Buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Cost	537,474	517,087
Machinery, equipment and other [Member]
Property, Plant and Equipment [Line Items]
Cost	$ 1,698,638	$ 1,596,085