Plant, Equipment and Timberlands (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Plant, equipment and timberlands
Accumulated depreciation	$ (915,777)	$ (850,255)
Subtotal	559,434	556,382
Construction in progress	52,782	34,576
Asset retirement obligation, net	6,374	7,968	9,717
Timberlands, less depletion	2,596	3,024
Total	621,186	601,950	608,200
Land and buildings [Member]
Plant, equipment and timberlands
Property, plant and equipment, gross	194,541	186,846
Machinery and equipment [Member]
Plant, equipment and timberlands
Property, plant and equipment, gross	1,158,245	1,102,709
Furniture, fixtures, and other [Member]
Plant, equipment and timberlands
Property, plant and equipment, gross	$ 122,425	$ 117,082

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 carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

Gross amount of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

Amount, net of accumulated depreciation, depletion and amortization, of long-lived physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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