Supplemental Oil And Gas Disclosures (Estimated Quantities Of Proved Oil And Gas Reserves) (Details)	1 Months Ended		12 Months Ended	1 Months Ended	12 Months Ended						1 Months Ended	12 Months Ended							12 Months Ended						12 Months Ended							12 Months Ended						12 Months Ended								1 Months Ended		12 Months Ended
	Feb. 28, 2010	Aug. 31, 2006	Dec. 31, 2011	Jun. 30, 2010 Oil Reserves [Member]	Dec. 31, 2011 Oil Reserves [Member] MBbls		Dec. 31, 2010 Oil Reserves [Member] MBbls		Dec. 31, 2009 Oil Reserves [Member] MBbls	Dec. 31, 2008 Oil Reserves [Member] MBbls	Jun. 30, 2010 Natural Gas Liquids Reserves [Member]	Dec. 31, 2011 Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2010 Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2009 Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2008 Natural Gas Liquids Reserves [Member] MMcf	Dec. 31, 2011 United States [Member] Oil Reserves [Member] MBbls		Dec. 31, 2010 United States [Member] Oil Reserves [Member] MBbls		Dec. 31, 2009 United States [Member] Oil Reserves [Member] MBbls	Dec. 31, 2008 United States [Member] Oil Reserves [Member] MBbls	Dec. 31, 2011 United States [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2010 United States [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2009 United States [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2008 United States [Member] Natural Gas Liquids Reserves [Member] MMcf	Dec. 31, 2011 United Kingdom [Member] Oil Reserves [Member] MBbls		Dec. 31, 2010 United Kingdom [Member] Oil Reserves [Member] MBbls		Dec. 31, 2009 United Kingdom [Member] Oil Reserves [Member] MBbls	Dec. 31, 2008 United Kingdom [Member] Oil Reserves [Member] MBbls	Dec. 31, 2011 United Kingdom [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2010 United Kingdom [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2009 United Kingdom [Member] Natural Gas Liquids Reserves [Member] MMcf		Dec. 31, 2008 United Kingdom [Member] Natural Gas Liquids Reserves [Member] MMcf		Feb. 28, 2010 Camelot Field [Member]	Dec. 31, 2009 Camelot Field [Member]	Dec. 31, 2009 Bushwood Field [Member] Natural Gas Liquids Reserves [Member]
Reserve Quantities [Line Items]
Proved reserves beginning balance					24,818		29,727		32,012			227,264		399,315		473,406			24,818		29,727		32,012		227,264		387,315		460,456											12,000	[1]	12,950	[1]
Revision of previous estimates				(1.8)	3,475	[2]	(1,555)	[3]	232		131,000,000,000	(108,947)	[4]	(144,954)	[5]	(45,370)	[6]		3,475	[2]	(1,555)	[3]	232		(108,947)	[4]	(132,954)	[5]	(44,615)	[6]			[2]		[3]				[1],[4]	(12,000)	[1],[5]	(755)	[1],[6]					38,000,000,000
Production					(5,785)		(3,354)		(2,741)			(17,458)		(27,097)		(27,334)			(5,785)		(3,354)		(2,741)		(17,458)		(27,097)		(27,139)										[1]			(195)	[1]
Purchases of reserves in place																																							[1]
Sales of reserves in place					(205)				(1)			(4,109)				(7,933)			(205)				(1)		(4,109)				(7,933)										[1]
Extensions and discoveries					386				225			271				6,546			386				225		271				6,546										[1]
Proved reserves ending balance					22,689		24,818		29,727			97,021		227,264		399,315			22,689		24,818		29,727		97,021		227,264		387,315										[1]			12,000	[1]
Total proved developed reserves					12,754		11,796		14,850	12,809		59,859		75,664		124,763		257,744	12,754		11,796		14,850	12,809	59,859		75,664		124,763		256,794								[1]		[1]		[1]	950	[1]
Ownership percentage																																															50.00%
Additional ownership percentage acquired																																														50.00%
Acquired working interest	50.00%	100.00%	50.00%																																											50.00%
Reclassification of estimate proved reserves			87,000,000,000

[1] Reflects 50% ownership in the Camelot field's reserves in 2009 and 2008. In February 2010 we acquired the other 50% ownership interest in the Camelot field. We no longer have any development plans for the field and we intend to fully abandon the field in 2012 in accordance with the applicable regulations in the United Kingdom. See Note 5 for additional information regarding our Camelot field.

[2] The positive revision reflects the better than expected production volumes primarily from our Phoenix field at Green Canyon Blocks 236, 237, 238 and 282 since it began production in October 2010.

[3] Includes an approximate 1.8 MMBbls decrease as reflected in our independent petroleum engineer reserve report at June 30, 2010 resulting from a combination of factors, including well performance issues at certain of our producing fields, most notably our Bushwood field at Garden Banks Blocks 462/463/506/507, as well as changes in the field economics of some of our other oil and gas properties. The changes in field economics primarily affected properties that were either close to the end of their production life or in which we had proved undeveloped reserves, which would have been required to be developed in the near term. The decision not to develop these properties in light of these economic changes was also driven by our desire to pursue potential alternatives to divest all or a portion of our oil and gas assets and the increasing uncertainties about future oil and gas operations in the Gulf of Mexico as a result of the oil spill from the Macondo well.

[4] Decrease primarily represents a reclassification of estimate proved reserves to the probable reserve category following the receipt and interpretation of new seismic data. The field with the largest shift from the proved to probable reserve category was our Bushwood field, where we reclassified approximately 87 Bcf at December 31, 2011.

[5] Includes an approximate 131 Bcf decrease as reflected in our independent petroleum engineer reserve report at June 30, 2010 resulting from a combination of factors, including well performance issues at certain of our producing fields, most notably our Bushwood field at Garden Banks Blocks 462/463/506/507, as well as changes in the field economics of some of our other oil and gas properties. The changes in field economics primarily affected properties that were either close to the end of their production life or in which we had proved undeveloped reserves, which would have been required to be developed in the near term. The decision not to develop these properties in light of these economic changes was also driven by our desire to pursue potential alternatives to divest all or a portion of our oil and gas assets and the increasing uncertainties about future oil and gas operations in the Gulf of Mexico as a result of the oil spill from the Macondo well.

[6] Includes a 38 Bcfe reduction of the proved reserves at Bushwood field reflecting certain reservoir issues for our Noonan Gas wells subsequent to their reestablishing sustained production in January 2009 and new geologic data collected throughout 2009.