Property, Plant and Equipment - Schedule (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 826,984	$ 813,761
Accumulated depreciation	483,595	459,964
Net property, plant and equipment	343,389	353,797
Land and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	74,510	73,980
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	234,272	231,219
Equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	482,241	472,407
Computer software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 35,961	$ 36,155