Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 555,281	$ 492,903
Less accumulated depreciation	(320,732)	(306,069)
Net	234,549	186,834
Land And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	21,913	21,573
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	45,400	40,667
Machinery, Equipment And Customer Capital [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	396,125	367,964
Computer Hardware And Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	21,098	19,014
Furniture And Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	9,056	8,637
Construction-In-Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 61,689	$ 35,048