|**Capitalized Exploratory Well Costs (Details) (USD $)In Millions, unless otherwise specified**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | 6 Months Ended                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                       
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Capitalized Exploratory Well Costs, Beginning of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | $ 696                                                                                                                                                                                                                                                                                                                                  |                                                                                                                                                                                                                                                                                                                                       
|Additions to Capitalized Exploratory Well Costs Pending Determination of Proved Reserves                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 160                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Reclassified to Proved Oil and Gas Properties Based on Determination of Proved Reserves                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | (9)                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Capitalized Exploratory Well Cost, Charged to Expense                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | (107)                                                                                                                                                                                                                                                                                                                                  | [1]                                                                                                                                                                                                                                                                                                                                   
|Other                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | (19)                                                                                                                                                                                                                                                                                                                                   | [2]                                                                                                                                                                                                                                                                                                                                   
|Capitalized Exploratory Well Costs, End of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 721                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs capitalized for a Period of One Year or Less                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 330                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 391                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Number of Projects with Exploratory Well Costs That Have Been Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                           | 8                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Capitalized Exploratory Well Costs, End of Period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 721                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 221                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 59                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 111                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 391                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Blocks O And I Offshore Equatorial Guinea                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 155                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 106                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 6                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 43                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 155                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                       
|YoYo Offshore Cameron                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 44                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 38                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 2                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 4                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 44                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Leviathan Offshore Israel                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 62                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 41                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 21                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 62                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Leviathan-1 Deep Offshore Israel                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 27                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 27                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 27                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Dalit Offshore Israel                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 22                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 21                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 1                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 0                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 22                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Gunflint Deepwater Gulf Of Mexico                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 68                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 56                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 3                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 9                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 68                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|Other - 2 Projects of $10 million or less                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|**Capitalized Exploratory Well Costs [Abstract]**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Exploratory Well Costs Capitalized for a Period Greater Than One Year Since Commencement of Drilling                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 13                                                                                                                                                                                                                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                       
|**Projects with Exploratory Well Costs Capitalized for More than One Year Since The Commencement of Drilling [Line Items]**                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2009 & prior                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | 0                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended since 2010                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 6                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Suspended Since 2011                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 7                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                                                                       
|Total                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | $ 13                                                                                                                                                                                                                                                                                                                                   |                                                                                                                                                                                                                                                                                                                                       
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     
|[1]
              Amount primarily represents the Deep Blue exploratory well (deepwater Gulf of Mexico) costs capitalized prior to December 31, 2011. Although hydrocarbons were found in both the initial exploration well and subsequent sidetrack, we and our partners have decided not to proceed with additional appraisal activities at this time.[2]
              Amount represents the Selkirk exploratory well (North Sea) which, along with our remaining North Sea assets, was reclassified to held for sale at June 30, 2012. See Note 3. Acquisitions and Divestitures. | [1]                                                                                                                                                                                                                                                                                                                                    | Amount primarily represents the Deep Blue exploratory well (deepwater Gulf of Mexico) costs capitalized prior to December 31, 2011. Although hydrocarbons were found in both the initial exploration well and subsequent sidetrack, we and our partners have decided not to proceed with additional appraisal activities at this time.
|[1]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Amount primarily represents the Deep Blue exploratory well (deepwater Gulf of Mexico) costs capitalized prior to December 31, 2011. Although hydrocarbons were found in both the initial exploration well and subsequent sidetrack, we and our partners have decided not to proceed with additional appraisal activities at this time.
|[2]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Amount represents the Selkirk exploratory well (North Sea) which, along with our remaining North Sea assets, was reclassified to held for sale at June 30, 2012. See Note 3. Acquisitions and Divestitures.                                                                                                                           

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                    duration X- DefinitionCapitalized exploratory well costs that were expensed during the year because proved reserves were not found at the exploratory well.+ 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)(3) -URI http://asc.fasb.org/extlink&oid=8451039&loc=SL6806780-109447+ Details**Name:**
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                    instant X- DefinitionThe amount of exploratory well costs that have been capitalized for a period of one year or less after the completion of drilling.+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS19-1 -Paragraph 10 -Subparagraph b -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 16 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e61939-109447+ Details**Name:**
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