Exploratory Costs (Schedule of Capitalized Exploratory Well Activity) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Costs Incurred, Oil and Gas Property Exploration Activities [Line Items]
Beginning Capitalized Exploratory Costs	$ 0
Additions to Exploratory Costs Pending Determination of Proved Reserves	7,373
Reclassification Due to Determination of Proved Reserves	(5,048)
Ending Capitalized Exploratory Costs	$ 2,325

Previously capitalized costs of the drilling of wells that were reclassified as part of the costs of the enterprise's wells and related equipment and facilities at the time that proved reserves were found.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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