Exploratory Costs (Schedule Of Capitalized Exploratory Well And Project Activity) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Exploratory Costs [Abstract]
Beginning capitalized exploratory costs	$ 107,596
Additions to exploratory costs pending the determination of proved reserves	174,894
Reclassification due to determination of proved reserves	(117,610)
Exploratory well costs charged to exploration expense	(26,878)
Ending capitalized exploratory costs	$ 138,002

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS19-1

-Paragraph 10

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Topic 932

-SubTopic 235

-Section 50

-Paragraph 1B

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6821537&loc=SL6806780-109447

Name:	us-gaap_ReclassificationToWellFacilitiesAndEquipmentBasedOnDeterminationOfProvedReserves
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration