Property, Plant and Equipment (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment
Gross property, plant and equipment	$ 2,267,740	$ 3,288,630
Less: Accumulated depreciation	(1,561,122)	(2,022,405)
Property, plant and equipment, net	706,618	1,266,225
Land
Property, Plant and Equipment
Gross property, plant and equipment	17,414	26,336
Land improvements
Property, Plant and Equipment
Gross property, plant and equipment	12,731	14,199
Buildings and improvements
Property, Plant and Equipment
Gross property, plant and equipment	175,008	190,078
Machinery and equipment
Property, Plant and Equipment
Gross property, plant and equipment	1,967,023	2,950,384
Uncompleted construction
Property, Plant and Equipment
Gross property, plant and equipment	$ 95,564	$ 107,633