Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Carrying values of property, plant and equipment
Land and land improvements	$ 34,005	$ 34,794
Buildings and leasehold improvements	137,639	150,133
Machinery and equipment	426,082	375,784
Computer equipment and software	66,498	61,988
Construction in process	21,566	25,702
Gross property, plant and equipment	685,790	648,401
Accumulated depreciation	(398,857)	(369,535)
Net property, plant and equipment	$ 286,933	$ 278,866