| **Asset Impairments (Tables)**              | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                        |
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| **Asset Impairment Charges [Abstract]**     |                                                                                                                                                                                                                                                                                                                                                                   |
| Asset Impairment Charges Pre Tax (non-cash) | Pre-tax (non-cash) asset impairment charges were as follows: Year Ended December 31,(millions)2015 2014 2013Onshore US$— $42 $39Deepwater Gulf of Mexico158 350 —Equatorial Guinea339 — —Eastern Mediterranean36 14 47North Sea— 94 —Total$533 $500 $86 |

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| - References
No definition available.
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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 FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6391110&loc=d3e2921-110230Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section CC -Subsection 3
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