| **Asset Impairments (Tables)**                        | 3 Months Ended                                                                                                                                                                                                                                                              |
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| **Asset Impairments [Abstract]**                      |                                                                                                                                                                                                                                                                        |
| Summary of details of impairment of long-lived assets | Pre-tax (non-cash) asset impairment charges were as follows: Three Months Ended March 31,(millions)2015 2014Deepwater Gulf of Mexico3 —Eastern Mediterranean24 —North Sea— 92Non-Core US Property— 5Total$27 $97 |

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| - Definition
Tabular disclosure for impairment of long-lived assets held and used by an entity which includes a description of the impaired long-lived asset and facts and circumstances leading to the impairment, aggregate amount of the impairment loss and where the loss is located in the income statement, method(s) for determining fair value, and the segment in which the impaired long-lived asset is reported.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section CC -Subsection 3Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230
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