Segment Information (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011	Dec. 31, 2010
Operating income (loss)
Profit sharing	$ (3,954,000)	$ (7,428,000)	$ (20,237,000)	$ (37,085,000)
Impairment charges	(7,894,000)		(7,894,000)
Operating income	72,721,000	108,785,000	296,236,000	502,330,000
Assets
Cash and equivalents	287,120,000	456,694,000	287,120,000	456,694,000	420,938,000	390,761,000	277,691,000	186,513,000
Income taxes receivable	939,000		939,000			16,722,000
Deferred income taxes	28,229,000		28,229,000			25,341,000
Property, plant and equipment, net	2,213,703,000		2,213,703,000			2,193,745,000
Other	134,363,000		134,363,000			134,264,000
Total assets	5,775,516,000	6,003,481,000	5,775,516,000	6,003,481,000		5,979,226,000
Liabilities
Accounts payable	377,213,000		377,213,000			420,824,000
Income taxes payable	12,014,000		12,014,000			10,880,000
Deferred income taxes	544,800,000		544,800,000			489,915,000
Liabilities	3,342,688,000	3,656,451,000	3,342,688,000	3,656,451,000
Other
Operating income (loss)
Corporate SG and A	(7,600,000)	(19,100,000)	(22,400,000)	(38,400,000)
Company-wide stock option expense		(3,600,000)	(5,700,000)	(11,000,000)
Profit sharing	(2,900,000)	(5,500,000)	(15,300,000)	(30,600,000)
Impairment charges	(7,900,000)		(7,900,000)
Other, net	600,000	(200,000)	2,000,000	1,900,000
Operating income	(17,759,000)	(28,437,000)	(49,294,000)	(78,115,000)
Assets
Cash and equivalents	246,800,000	391,500,000	246,800,000	391,500,000
Income taxes receivable	900,000	24,500,000	900,000	24,500,000
Deferred income taxes	28,200,000	21,600,000	28,200,000	21,600,000
Property, plant and equipment, net	75,700,000	72,100,000	75,700,000	72,100,000
Debt issuance costs, net	29,400,000	25,600,000	29,400,000	25,600,000
Intra-company debt	129,100,000	130,600,000	129,100,000	130,600,000
Other	87,200,000	91,400,000	87,200,000	91,400,000
Total assets	597,297,000	757,275,000	597,297,000	757,275,000
Liabilities
Accounts payable	32,300,000	32,600,000	32,300,000	32,600,000
Income taxes payable	12,700,000	15,000,000	12,700,000	15,000,000
Accrued interest	28,900,000	61,800,000	28,900,000	61,800,000
Accrued profit sharing	15,500,000	31,400,000	15,500,000	31,400,000
Debt	2,156,200,000	2,342,000,000	2,156,200,000	2,342,000,000
Deferred income taxes	240,900,000	221,000,000	240,900,000	221,000,000
Other liabilities	18,500,000	81,800,000	18,500,000	81,800,000
Liabilities	$ 2,505,036,000	$ 2,785,613,000	$ 2,505,036,000	$ 2,785,613,000