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.

+ References+ Details

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.

+ References+ Details

- 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.

+ References+ Details

- 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.

+ References+ Details

Property, Plant & Equipment (Details) (USD $)	3 Months Ended		6 Months Ended
Property, Plant & Equipment (Details) (USD $)	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Property, Plant and Equipment [Line Items]
Less accumulated depreciation	$ (261,380,000)		$ (261,380,000)		$ (252,531,000)
Total property, plant and equipment, net	243,307,000		243,307,000		203,717,000
Depreciation expense related to property, plant and equipment	5,200,000	4,800,000	10,300,000	9,400,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	21,273,000		21,273,000		19,775,000
Land improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	10,451,000		10,451,000		10,449,000
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	134,955,000		134,955,000		106,199,000
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	301,615,000		301,615,000		289,579,000
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	6,881,000		6,881,000		6,839,000
Computer equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 29,512,000		$ 29,512,000		$ 23,407,000