Segment Information (Details 2) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Operating income (loss)
Profit sharing	$ (8,469,000)	$ (3,954,000)	$ (19,891,000)	$ (20,237,000)
Impairment charges		(7,894,000)	(308,000)	(7,894,000)
Operating income	113,273,000	72,721,000	278,703,000	296,236,000
Assets
Cash and equivalents	370,056,000	287,120,000	370,056,000	287,120,000	243,753,000	375,917,000	420,938,000	390,761,000
Deferred income taxes	25,228,000		25,228,000			23,449,000
Property, plant and equipment, net	2,241,067,000		2,241,067,000			2,231,198,000
Other	120,742,000		120,742,000			132,816,000
Total assets	5,874,305,000	5,775,516,000	5,874,305,000	5,775,516,000		5,815,416,000
Liabilities
Accounts payable	426,406,000		426,406,000			360,097,000
Income taxes payable	7,649,000		7,649,000			16,941,000
Accrued interest	23,060,000		23,060,000			35,306,000
Deferred income taxes	565,798,000		565,798,000			537,304,000
Liabilities	3,316,517,000	3,342,688,000	3,316,517,000	3,342,688,000
Other
Operating income (loss)
Corporate SG & A	(9,200,000)	(7,600,000)	(26,300,000)	(22,400,000)
Company-wide equity- based compensation	(2,100,000)		(7,300,000)	(5,700,000)
Profit sharing	(7,400,000)	(2,900,000)	(16,500,000)	(15,300,000)
Impairment charges		(7,900,000)		(7,900,000)
Other, net	1,400,000	600,000	2,000,000	2,000,000
Operating income	(17,274,000)	(17,759,000)	(48,147,000)	(49,294,000)
Assets
Cash and equivalents	325,800,000	246,800,000	325,800,000	246,800,000
Income taxes receivable		900,000		900,000
Deferred income taxes	25,200,000	28,200,000	25,200,000	28,200,000
Property, plant and equipment, net	72,900,000	75,700,000	72,900,000	75,700,000
Debt issuance costs, net	27,700,000	29,400,000	27,700,000	29,400,000
Intra-company debt	153,600,000	129,100,000	153,600,000	129,100,000
Other	94,000,000	87,200,000	94,000,000	87,200,000
Total assets	699,244,000	597,297,000	699,244,000	597,297,000
Liabilities
Accounts payable	43,100,000	32,300,000	43,100,000	32,300,000
Income taxes payable	7,700,000	12,700,000	7,700,000	12,700,000
Accrued interest	22,900,000	28,900,000	22,900,000	28,900,000
Accrued profit sharing		15,500,000		15,500,000
Debt	2,041,800,000	2,156,200,000	2,041,800,000	2,156,200,000
Deferred income taxes	204,600,000	240,900,000	204,600,000	240,900,000
Other	46,200,000	18,500,000	46,200,000	18,500,000
Liabilities	$ 2,366,273,000	$ 2,505,036,000	$ 2,366,273,000	$ 2,505,036,000