|**Capitalized Exploratory Well Costs (Details) (USD $)In Millions, unless otherwise specified**                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 9 Months Ended                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                     
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Capitalized Exploratory Well Costs, Beginning of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | $ 696                                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                                                     
|Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | 164                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | (27)                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                     
|Capitalized Exploratory Well Cost, Charged to Expense                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | (108)                                                                                                                                                                                                                                                                                                                | [1]                                                                                                                                                                                                                                                                                                                 
|Other                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | (19)                                                                                                                                                                                                                                                                                                                 | [2]                                                                                                                                                                                                                                                                                                                 
|Capitalized Exploratory Well Costs, End of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 706                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs capitalized for a Period of One Year or Less                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 301                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 405                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                     | 9                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Capitalized Exploratory Well Costs, End of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 706                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 219                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Suspended Since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 56                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 130                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 405                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|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                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 156                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 44                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 156                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                     
|YoYo Offshore Cameron                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 45                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 5                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 45                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Leviathan Offshore Israel                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 78                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 37                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 78                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|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                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 28                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 28                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 28                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|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                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 22                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Cyprus A-1 Offshore Cyprus                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 10                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 10                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 10                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|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                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 54                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                     
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 54                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|Suspended Since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 54                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|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                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 12                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                     
|**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                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 6                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                     
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                            | $ 12                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                     
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
|[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 decided not to proceed with additional appraisal activities.[2]
              Amount represents the Selkirk exploratory well (North Sea) which, along with our other North Sea assets, was reclassified to held for sale at June 30, 2012. See Note 3. Acquisitions and Divestitures. | [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 decided not to proceed with additional appraisal activities.
|[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 decided not to proceed with additional appraisal activities.
|[2]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Amount represents the Selkirk exploratory well (North Sea) which, along with our other North Sea assets, was reclassified to held for sale at June 30, 2012. See Note 3. Acquisitions and Divestitures.                                                                                                             

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                    duration X- DefinitionPreviously 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.+ ReferencesReference 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=8451039&loc=SL6806780-109447+ Details**Name:**
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