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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Property, Plant and Equipment (Details) (USD $)	12 Months Ended
Property, Plant and Equipment (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1,248,649,000	$ 1,238,422,000
Accumulated Depreciation and Depletion	(930,515,000)	(905,625,000)
Property, Plant and Equipment, Net	318,134,000	332,797,000
Depreciation and depletion expense	55,900,000	61,200,000	69,000,000
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	27,370,000	27,334,000
Quarries/mining properties [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	39,596,000	39,596,000
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	147,115,000	144,348,000
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	911,753,000	918,450,000
Construction in progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	31,060,000	13,438,000
Furniture and fixtures and other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 91,755,000	$ 95,256,000