Guarantor Subsidiaries (Income Statement) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues	$ 97,615	$ 83,275	$ 23,003	$ 15,166	$ 16,632	$ 10,302	$ 19,053	$ 14,104	$ 219,058	$ 60,091	$ 71,675
Operating expenses	59,857	64,174	41,359	33,867	50,800	42,524	18,304	16,077	58,536	17,668	15,347
DD&A									66,564	26,478	28,894
Impairment of oil and gas properties	6,000	11,400	20,000	15,700	36,900	28,800	0	0	53,072	65,706	7,692
General and administrative									21,085	17,853	18,415
Income (Loss) From Operations	37,758	19,101	(18,356)	(18,701)	(34,168)	(32,222)	749	(1,973)	19,801	(67,614)	1,327
Derivatives:
Realized Gain Loss On Derivatives									0	0	(11,753)
Unrealized gains (losses)									5,141	8,378	12,291
Interest expense									(84,122)	(44,893)	(34,592)
Sales of reserves in place									0	0	87,171
Letter of credit fees									(21,903)	0	0
Gains (Losses) on Extinguishment of Debt									(21,661)	(402)	0
Other income (expense)									(9,254)	597	1,299
Income (Loss) Before Income Taxes									(111,998)	(103,934)	55,743
Income Tax Expense (Benefit)									14,228	27,061	(788)
Net Income (Loss)									(126,226)	(130,995)	56,531
Preferred Stock Dividends:									1,823	1,974	2,227
Net Income (Loss) to Common Shareholders	(6,910)	(34,158)	(51,264)	(35,718)	(45,101)	(63,756)	(16,110)	(8,002)	(128,049)	(132,969)	54,304
[ParentCompanyMember]
Revenues									0	0	0
Operating expenses									0	0	(19)
DD&A									0	0	0
Impairment of oil and gas properties									0	0	0
General and administrative									2,629	2,198	2,629
Income (Loss) From Operations									(2,629)	(2,198)	(2,610)
Derivatives:
Realized Gain Loss On Derivatives									0	0	0
Unrealized gains (losses)									(705)	(2,642)	2,258
Interest expense									(54,241)	(10,623)	(11,476)
Sales of reserves in place											0
Letter of credit fees									0
Gains (Losses) on Extinguishment of Debt									0	(402)
Other income (expense)									0	(211)	(1)
Income (Loss) Before Income Taxes									(57,575)	(16,076)	(11,829)
Income Tax Expense (Benefit)									0	0	0
Net Income (Loss)									(57,575)	(16,076)	(11,829)
Preferred Stock Dividends:									1,823	1,974	2,227
Net Income (Loss) to Common Shareholders									(59,398)	(18,050)	(14,056)
[GuarantorSubsidiariesMember]
Revenues									11,877	18,337	11,174
Operating expenses									6,968	9,046	4,280
DD&A									8,603	11,490	6,202
Impairment of oil and gas properties									53,072	65,706	7,692
General and administrative									9,887	10,789	11,465
Income (Loss) From Operations									(66,653)	(78,694)	(18,465)
Derivatives:
Realized Gain Loss On Derivatives									0	0	0
Unrealized gains (losses)									0	0	0
Interest expense									(951)	(3,964)	(591)
Sales of reserves in place											0
Letter of credit fees									0
Gains (Losses) on Extinguishment of Debt									0	0
Other income (expense)									33,796	(678)	(93)
Income (Loss) Before Income Taxes									(33,808)	(83,336)	(19,149)
Income Tax Expense (Benefit)									0	3	0
Net Income (Loss)									(33,808)	(83,339)	(19,149)
Preferred Stock Dividends:									0	0	0
Net Income (Loss) to Common Shareholders									(33,808)	(83,339)	(19,149)
[NonGuarantorSubsidiariesMember]
Revenues									207,181	41,754	60,501
Operating expenses									51,568	8,622	11,086
DD&A									57,961	14,988	22,692
Impairment of oil and gas properties									0	0	0
General and administrative									8,569	4,866	4,321
Income (Loss) From Operations									89,083	13,278	22,402
Derivatives:
Realized Gain Loss On Derivatives									0	0	(11,753)
Unrealized gains (losses)									5,846	11,020	10,033
Interest expense									(67,673)	(38,894)	(25,079)
Sales of reserves in place											87,171
Letter of credit fees									(21,903)
Gains (Losses) on Extinguishment of Debt									(21,661)	0
Other income (expense)									(4,307)	10,074	3,947
Income (Loss) Before Income Taxes									(20,615)	(4,522)	86,721
Income Tax Expense (Benefit)									21,225	27,058	(788)
Net Income (Loss)									(41,840)	(31,580)	87,509
Preferred Stock Dividends:									0	0	0
Net Income (Loss) to Common Shareholders									(41,840)	(31,580)	87,509
[ConsolidationEliminationsMember]
Revenues									0	0	0
Operating expenses									0	0	0
DD&A									0	0	0
Impairment of oil and gas properties									0	0	0
General and administrative									0	0	0
Income (Loss) From Operations									0	0	0
Derivatives:
Realized Gain Loss On Derivatives									0	0	0
Unrealized gains (losses)									0	0	0
Interest expense									38,743	8,588	2,554
Sales of reserves in place											0
Letter of credit fees									0
Gains (Losses) on Extinguishment of Debt									0	0
Other income (expense)									(38,743)	(8,588)	(2,554)
Income (Loss) Before Income Taxes									0	0	0
Income Tax Expense (Benefit)									(6,997)	0	0
Net Income (Loss)									6,997	0	0
Preferred Stock Dividends:									0	0	0
Net Income (Loss) to Common Shareholders									$ 6,997	$ 0	$ 0