Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Property, Plant and Equipment
Gross property, plant and equipment	$ 3,308,262	$ 3,275,728
Less accumulated depreciation	(2,029,141)	(2,001,244)
Property, plant and equipment, net	1,279,121	1,274,484
Land
Property, Plant and Equipment
Gross property, plant and equipment	27,273	26,729
Land improvements
Property, Plant and Equipment
Gross property, plant and equipment	18,684	17,960
Buildings and improvements
Property, Plant and Equipment
Gross property, plant and equipment	192,788	186,799
Machinery and equipment
Property, Plant and Equipment
Gross property, plant and equipment	3,003,796	2,977,521
Uncompleted construction
Property, Plant and Equipment
Gross property, plant and equipment	$ 65,721	$ 66,719

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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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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