Property, Plant and Equipment, Net (Details) (USD $)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment, net
Original cost of fully depreciated assets still in use	$ 122,600,000	$ 98,600,000
Depreciation expense	16,300,000	16,800,000	19,700,000
Property, Plant and Equipment
Property, plant and equipment, gross	394,705,000	357,932,000
Accumulated depreciation and amortization	(201,540,000)	(189,751,000)
Property, plant and equipment excluding capital projects in progress, net	193,165,000	168,181,000
Capital projects in progress	2,551,000	8,891,000
Property, plant and equipment, net	195,716,000	177,072,000
Land
Property, Plant and Equipment
Property, plant and equipment, gross	28,996,000	26,384,000
Buildings and site improvements
Property, Plant and Equipment
Property, plant and equipment, gross	153,597,000	141,834,000
Leasehold improvements
Property, Plant and Equipment
Property, plant and equipment, gross	3,820,000	3,693,000
Machinery and equipment
Property, Plant and Equipment
Property, plant and equipment, gross	$ 208,292,000	$ 186,021,000

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

Gross amount, at the balance sheet date, of long-lived physical assets used in the normal conduct of business and not intended for resale. This can include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

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- Definition

Tangible assets that are held by an entity for use in the production or supply of goods and services, for rental to others, or for administrative purposes and that are expected to provide economic benefit for more than one year; net of accumulated depreciation. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

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