Condensed Consolidated Statements Of Equity (USD $)		Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings (Defecit) [Member]	Total [Member]	Restricted Stock [Member]
Balances at Dec. 31, 2011			$ 1,770,000	$ 737,015,000	$ (46,351,000)	$ 214,858,000	$ 354,627,000	$ 1,261,919,000
Net income (loss)		(211,565,000)					(211,565,000)	(211,565,000)
Hedge derivative contract settlements reclassified into earnings from AOCI, net of income tax						(28,589,000)		(28,589,000)
Net change in derivative fair value, net of income tax		61,287,000				61,287,000		61,287,000
Foreign currency translation adjustment		1,451,000				1,451,000		1,451,000
Issuance and vesting of stock compensation			19,000	5,610,000	(2,341,000)			3,288,000
Stock option exercises			1,000	10,000				11,000
Balances at Mar. 31, 2012	[1]		1,790,000	742,635,000	(48,692,000)	249,007,000	143,062,000	1,087,802,000
Balances at Dec. 31, 2012			1,790,000	751,394,000	(49,495,000)	161,493,000	(1,997,979,000)	(1,132,797,000)
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized									26,900,000
Net income (loss)		(59,707,000)					(59,707,000)	(59,707,000)
Hedge derivative contract settlements reclassified into earnings from AOCI, net of income tax						(14,755,000)		(14,755,000)
Net change in derivative fair value, net of income tax		0
Foreign currency translation adjustment		301,000				301,000		301,000
Issuance and vesting of stock compensation			39,000	4,994,000	(1,007,000)			4,026,000
Balances at Mar. 31, 2013			$ 1,829,000	$ 756,388,000	$ (50,502,000)	$ 147,039,000	$ (2,057,686,000)	$ (1,202,932,000)

[1] (1) Note 1 contains additional information