Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Accumulated Depreciation and Amortization	$ 229,540	$ 208,724
Property, Plant and Equipment, Net	108,775	103,487
Depreciation expense	36,780	36,728	34,163
Land [Member]
Property, Plant and Equipment [Line Items]
Gross Property, Plant and Equipment	4,228	4,194
Buildings [Member]
Property, Plant and Equipment [Line Items]
Gross Property, Plant and Equipment	69,871	68,077
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Gross Property, Plant and Equipment	$ 264,216	$ 239,940