Guarantor Subsidiaries (Cash Flow Statement)(Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Flows from Operating Activities:
Net Income (Loss)	$ (126,226)	$ (130,995)	$ 56,531
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	66,564	26,478	28,894
Impairment of oil and gas properties	53,072	65,706	7,692
Deferred tax expense (benefit)	(17,594)	21,116	(3,367)
Unrealized gains on derivatives	(5,141)	(8,378)	(12,291)
Gain on sales of reserves in place	0	0	87,171
Amortization of non-cash compensation	4,401	3,697	3,692
Amortization of loan costs and discount	14,179	12,234	10,262
Gains (Losses) on Extinguishment of Debt	21,661	402	0
Non-cash interest expense	8,684	12,811	8,764
Other	15,365	1,518	(2,086)
Changes in operating assets and liabilities:
(Increase) decrease in receivables	(24,319)	(531)	6,732
(Increase) decrease in other current assets	(592)	(13,328)	(4,668)
Increase (decrease) in liabilities	28,559	(30,073)	4,035
Net Cash Provided by (Used in) Operating Activities	38,613	(39,343)	17,019
Cash Flows From Investing Activities:
Capital expenditures	(246,925)	(165,062)	(92,007)
Acquisitions, net of cash acquired	(238,854)	(33,075)	(43,726)
Proceeds from sales, net of cash	1,407	0	108,316
Issuance of note receivable to affiliates	0		0
(Increase) Decrease in restricted cash	(178)	31,726	(28,897)
Net Cash Provided by (Used in) Investing Activities	(484,550)	(166,411)	(56,314)
Cash Flows From Financing Activities:
Repayments of borrowings	(274,629)	(103,225)	(75,342)
Borrowings under debt agreements, net of debt discount	654,023	210,000	185,000
Proceeds from issuance of common stock	60,805	118,444	30,181
Dividends paid	(1,665)	(1,816)	(2,070)
Payments for early extinguishment of debt	(7,248)	0	0
Financing costs paid	(32,204)	(11,401)	(26,590)
Other financing	4	521	96
Net Cash Provided by (Used in) Financing Activities	399,086	212,523	111,275
Net Increase (Decrease) in Cash and Cash Equivalents	(46,851)	6,769	71,980
Cash and Cash Equivalents, Beginning of Period	106,036	99,267	27,287
Cash and Cash Equivalents, End of Period	59,185	106,036	99,267
[ParentCompanyMember]
Cash Flows from Operating Activities:
Net Income (Loss)	(57,575)	(16,076)	(11,829)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	0	0	0
Impairment of oil and gas properties	0	0	0
Deferred tax expense (benefit)	0	0	0
Unrealized gains on derivatives	705	2,642	(2,258)
Gain on sales of reserves in place			0
Amortization of non-cash compensation	854	624	689
Amortization of loan costs and discount	6,908	1,049	537
Gains (Losses) on Extinguishment of Debt	0	402
Non-cash interest expense	445	880	1,010
Other	283	(82)	307
Changes in operating assets and liabilities:
(Increase) decrease in receivables	0	0	0
(Increase) decrease in other current assets	0	34	1,252
Increase (decrease) in liabilities	(493,026)	(134,457)	(17,915)
Net Cash Provided by (Used in) Operating Activities	(541,406)	(144,984)	(28,207)
Cash Flows From Investing Activities:
Capital expenditures	0	0	0
Acquisitions, net of cash acquired	0	0	0
Proceeds from sales, net of cash	0		0
Issuance of note receivable to affiliates	0		0
(Increase) Decrease in restricted cash	0	0	0
Net Cash Provided by (Used in) Investing Activities	0	0	0
Cash Flows From Financing Activities:
Repayments of borrowings	(32,457)	(101,250)	0
Borrowings under debt agreements, net of debt discount	538,860	135,000	0
Proceeds from issuance of common stock	60,805	118,444	30,181
Dividends paid	(1,665)	(1,816)	(2,070)
Payments for early extinguishment of debt	0
Financing costs paid	(24,141)	(5,926)	0
Other financing	4	532	96
Net Cash Provided by (Used in) Financing Activities	541,406	144,984	28,207
Net Increase (Decrease) in Cash and Cash Equivalents	0	0	0
Cash and Cash Equivalents, Beginning of Period	0	0	0
Cash and Cash Equivalents, End of Period	0	0	0
[GuarantorSubsidiariesMember]
Cash Flows from Operating Activities:
Net Income (Loss)	(33,808)	(83,339)	(19,149)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	8,603	11,490	6,202
Impairment of oil and gas properties	53,072	65,706	7,692
Deferred tax expense (benefit)	0	0	0
Unrealized gains on derivatives	0	0	0
Gain on sales of reserves in place			0
Amortization of non-cash compensation	0	0	0
Amortization of loan costs and discount	5	(403)	0
Gains (Losses) on Extinguishment of Debt	0	0
Non-cash interest expense	0	0	0
Other	173	105	(20)
Changes in operating assets and liabilities:
(Increase) decrease in receivables	1,495	(1,597)	(829)
(Increase) decrease in other current assets	(9,223)	2,872	(4,907)
Increase (decrease) in liabilities	546,749	95,725	85,445
Net Cash Provided by (Used in) Operating Activities	567,066	90,559	74,434
Cash Flows From Investing Activities:
Capital expenditures	(39,794)	(80,279)	(34,036)
Acquisitions, net of cash acquired	(2,372)	(8,027)	(42,542)
Proceeds from sales, net of cash	0		1
Issuance of note receivable to affiliates	(500,000)		0
(Increase) Decrease in restricted cash	(50)	0	2,450
Net Cash Provided by (Used in) Investing Activities	(542,216)	(88,306)	(74,127)
Cash Flows From Financing Activities:
Repayments of borrowings	0	0	0
Borrowings under debt agreements, net of debt discount	0	0
Proceeds from issuance of common stock	0	0	0
Dividends paid	0	0	0
Payments for early extinguishment of debt	0
Financing costs paid	0	0	0
Other financing	0	(11)	0
Net Cash Provided by (Used in) Financing Activities	0	(11)	0
Net Increase (Decrease) in Cash and Cash Equivalents	24,849	2,242	307
Cash and Cash Equivalents, Beginning of Period	2,951	709	402
Cash and Cash Equivalents, End of Period	27,800	2,951	709
[NonGuarantorSubsidiariesMember]
Cash Flows from Operating Activities:
Net Income (Loss)	(41,840)	(31,580)	87,509
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	57,961	14,988	22,692
Impairment of oil and gas properties	0	0	0
Deferred tax expense (benefit)	(10,597)	21,116	(3,367)
Unrealized gains on derivatives	(5,846)	(11,020)	(10,033)
Gain on sales of reserves in place			87,171
Amortization of non-cash compensation	0	0	0
Amortization of loan costs and discount	7,266	11,588	9,725
Gains (Losses) on Extinguishment of Debt	21,661	0
Non-cash interest expense	8,239	11,931	7,754
Other	14,909	1,495	(2,373)
Changes in operating assets and liabilities:
(Increase) decrease in receivables	(25,814)	1,066	7,561
(Increase) decrease in other current assets	8,631	(16,234)	(1,013)
Increase (decrease) in liabilities	(21,617)	11,732	(3,242)
Net Cash Provided by (Used in) Operating Activities	12,953	15,082	28,042
Cash Flows From Investing Activities:
Capital expenditures	(207,131)	(84,783)	(57,971)
Acquisitions, net of cash acquired	(236,482)	(25,048)	(1,184)
Proceeds from sales, net of cash	1,407		108,315
Issuance of note receivable to affiliates	0		(57,250)
(Increase) Decrease in restricted cash	(128)	31,726	(31,347)
Net Cash Provided by (Used in) Investing Activities	(442,334)	(78,105)	(39,437)
Cash Flows From Financing Activities:
Repayments of borrowings	(242,172)	(1,975)	(75,342)
Borrowings under debt agreements, net of debt discount	115,163	75,000	185,000
Proceeds from issuance of common stock	0	0	0
Dividends paid	0	0	0
Payments for early extinguishment of debt	(7,248)
Financing costs paid	(8,063)	(5,475)	(26,590)
Other financing	0	0	0
Net Cash Provided by (Used in) Financing Activities	357,680	67,550	83,068
Net Increase (Decrease) in Cash and Cash Equivalents	(71,700)	4,527	71,673
Cash and Cash Equivalents, Beginning of Period	103,085	98,558	26,885
Cash and Cash Equivalents, End of Period	31,385	103,085	98,558
[ConsolidationEliminationsMember]
Cash Flows from Operating Activities:
Net Income (Loss)	6,997	0	0
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation, depletion and amortization	0	0	0
Impairment of oil and gas properties	0	0	0
Deferred tax expense (benefit)	(6,997)	0	0
Unrealized gains on derivatives	0	0	0
Gain on sales of reserves in place			0
Amortization of non-cash compensation	3,547	3,073	3,003
Amortization of loan costs and discount	0	0	0
Gains (Losses) on Extinguishment of Debt	0	0
Non-cash interest expense	0	0	0
Other	0	0	0
Changes in operating assets and liabilities:
(Increase) decrease in receivables	0	0	0
(Increase) decrease in other current assets	0	0	0
Increase (decrease) in liabilities	(3,547)	(3,073)	(60,253)
Net Cash Provided by (Used in) Operating Activities	0	0	(57,250)
Cash Flows From Investing Activities:
Capital expenditures	0	0	0
Acquisitions, net of cash acquired	0	0	0
Proceeds from sales, net of cash	0		0
Issuance of note receivable to affiliates	500,000		57,250
(Increase) Decrease in restricted cash	0	0	0
Net Cash Provided by (Used in) Investing Activities	500,000	0	57,250
Cash Flows From Financing Activities:
Repayments of borrowings	0	0	0
Borrowings under debt agreements, net of debt discount	0	0	0
Proceeds from issuance of common stock	0	0	0
Dividends paid	0	0	0
Payments for early extinguishment of debt	0
Financing costs paid	0	0	0
Other financing	0	0	0
Net Cash Provided by (Used in) Financing Activities	(500,000)	0	0
Net Increase (Decrease) in Cash and Cash Equivalents	0	0	0
Cash and Cash Equivalents, Beginning of Period	0	0	0
Cash and Cash Equivalents, End of Period	$ 0	$ 0	$ 0