Capitalized Exploratory Well Costs (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Capitalized Exploratory Well Costs [Abstract]
Capitalized Exploratory Well Costs, Beginning of Period	$ 696
Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves	160
Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves	(9)
Capitalized Exploratory Well Cost, Charged to Expense	(107)	[1]
Other	(19)	[2]
Capitalized Exploratory Well Costs, End of Period	721
Exploratory Well Costs capitalized for a Period of One Year or Less	330		318
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	391		378
Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling	8		9
Capitalized Exploratory Well Costs, End of Period	721
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	221
Suspended since 2010	59
Suspended Since 2011	111
Total	391		378
Blocks O And I Offshore Equatorial Guinea
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	155
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	106
Suspended since 2010	6
Suspended Since 2011	43
Total	155
YoYo Offshore Cameron
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	44
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	38
Suspended since 2010	2
Suspended Since 2011	4
Total	44
Leviathan Offshore Israel
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	62
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	0
Suspended since 2010	41
Suspended Since 2011	21
Total	62
Leviathan-1 Deep Offshore Israel
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	27
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	0
Suspended since 2010	0
Suspended Since 2011	27
Total	27
Dalit Offshore Israel
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	22
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	21
Suspended since 2010	1
Suspended Since 2011	0
Total	22
Gunflint Deepwater Gulf Of Mexico
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	68
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	56
Suspended since 2010	3
Suspended Since 2011	9
Total	68
Other - 2 Projects of $10 million or less
Capitalized Exploratory Well Costs [Abstract]
Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling	13
Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]
Suspended since 2009 & prior	0
Suspended since 2010	6
Suspended Since 2011	7
Total	$ 13

[1] Amount primarily represents the Deep Blue exploratory well (deepwater Gulf of Mexico) costs capitalized prior to December 31, 2011. Although hydrocarbons were found in both the initial exploration well and subsequent sidetrack, we and our partners have decided not to proceed with additional appraisal activities at this time.

[2] Amount represents the Selkirk exploratory well (North Sea) which, along with our remaining North Sea assets, was reclassified to held for sale at June 30, 2012. See Note 3. Acquisitions and Divestitures.