Fair Value Measurements (Details Textuals) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Year FinancialInstitution CreditFacility Project Well CommercialBank	Sep. 30, 2010	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment on Oil and Gas Properties	$ 38,681,000		$ 38,681,000	$ 6,505,000
Proceeds from sale of oil and gas properties			66,213,000	327,454,000
Fair Value Measurements (Textuals) [Abstract]
Interest and dividends	84,000	44,000	179,000	118,000
Mark-to-market gain (loss)	(7,900,000)	3,500,000	(6,600,000)	8,200,000
Allowance for uncollectible receivables	4,200,000		4,200,000		5,000,000
Number of financial institutions included in counterparties			10
Number of secured lenders in bank credit facility			9
Net derivative receivable	15,400,000		15,400,000
6.375% Senior Subordinated Notes due 2015 [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	6.375%		6.375%		6.375%
7.5% senior subordinated notes due 2016, net of discount [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	7.50%		7.50%		7.50%
7.5% Senior Subordinated Notes due 2017 [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	7.50%		7.50%		7.50%
7.25% Senior Subordinated Notes due 2018 [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	7.25%		7.25%		7.25%
8.0% senior subordinated notes due 2019, net of discount [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	8.00%		8.00%		8.00%
6.75% Senior Subordinated Notes due 2020 [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	6.75%		6.75%		6.75%
5.75% Senior Subordinated Notes due 2021 [Member]
Debt Instrument [Line Items]
Interest rate on senior subordinated notes	5.75%		5.75%		5.75%
East Texas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment on Oil and Gas Properties	31,200,000
Proceeds from sale of oil and gas properties	11,000,000		11,000,000
Gulf Coast [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment on Oil and Gas Properties	$ 7,500,000			$ 6,500,000