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Oil And Gas Properties (Narrative) (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Oil And Gas Properties [Abstract]
Asset retirement obligation	$ 229,035,000	$ 254,391,000
Capitalized exploration cost	$ 7,800,000

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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