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Supplemental Oil And Gas Disclosures (Costs Incurred In Oil And Natural Gas Property Acquisition, Exploration And Development Activities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Supplemental Oil And Gas Disclosures [Abstract]
Proved oil and gas properties	$ 3,356	$ 20,259	$ 35,134
Unproved oil and gas properties	15,197	81,624	13,917
Exploration costs	1,685	297	1,019
Development costs	618,737	243,758	38,526
Asset retirement costs	5,055	968	1,314
Total costs incurred	$ 644,030	$ 346,906	$ 89,910

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Cost incurred, including capitalized costs and costs charged to expense, in acquisition of oil and gas properties.

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Costs incurred, including capitalized costs and costs charged to expense, associated with the acquisition of oil and gas properties that have proved reserves.

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Amount of asset retirement obligations (ARO) costs incurred (whether capitalized or charged to expense) during the period.

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Development costs incurred, including capitalized costs and costs charged to expense, in oil and gas activities.

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