Property, Plant and Equipment (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Property, Plant and Equipment
Property, plant and equipment, gross	$ 929,942	$ 910,695
Less: Accumulated depreciation	631,793	604,899
Property, plant and equipment, net	298,149	305,796
Land [Member]
Property, Plant and Equipment
Property, plant and equipment, gross	33,068	32,775
Building [Member]
Property, Plant and Equipment
Property, plant and equipment, gross	204,809	201,866
Machinery and equipment [Member]
Property, Plant and Equipment
Property, plant and equipment, gross	677,112	663,642
Construction in Progress [Member]
Property, Plant and Equipment
Property, plant and equipment, gross	$ 14,953	$ 12,412