| **Segment Information (Details) (USD $)In Millions, unless otherwise specified** | 3 Months Ended | 6 Months Ended |         |
|----------------------------------------------------------------------------------|----------------|----------------|---------|
||
| **Segment Reporting Information [Line Items]**                                   |           |           |    |   |   |
| Revenues from Third Parties                                                      | $ 1,338        | $ 1,112        | $ 2,665 | $ 2,196 |   |
| Income from Equity Method Investees                                              | 45             | 37             | 97      | 96 |   |
| Total Revenues                                                                   | 1,383          | 1,149          | 2,762   | 2,292 |   |
| DD&A                                                                         | 413            | 368            | 837     | 734 |   |
| (Gain) Loss on Divestitures                                                      | (44)           | 4              | (42)    | (12) |   |
| Asset Impairments                                                                | 34             | 0              | 131     | 0 |   |
| Income (Loss) from Continuing Operations Before Income Taxes                     | 233            | 486            | 510     | 804 |   |
| Total Assets                                                                     | 20,575         |           | 20,575  |   | 19,598 |
| United States [Member]                                                           |           |           |    |   |   |
| **Segment Reporting Information [Line Items]**                                   |           |           |    |   |   |
| Revenues from Third Parties                                                      | 842            | 683            | 1,684   | 1,399 |   |
| Income from Equity Method Investees                                              | 0              | 0              | 0       | 0 |   |
| Total Revenues                                                                   | 842            | 683            | 1,684   | 1,399 |   |
| DD&A                                                                         | 311            | 258            | 619     | 524 |   |
| (Gain) Loss on Divestitures                                                      | (8)            | 0              | (6)     | (12) |   |
| Asset Impairments                                                                | 18             | 0              | 23      | 0 |   |
| Income (Loss) from Continuing Operations Before Income Taxes                     | 199            | 320            | 382     | 563 |   |
| Total Assets                                                                     | 14,175         |           | 14,175  |   | 13,094 |
| Africa [Member]                                                                  |           |           |    |   |   |
| **Segment Reporting Information [Line Items]**                                   |           |           |    |   |   |
| Revenues from Third Parties                                                      | 339            | 290            | 662     | 563 |   |
| Income from Equity Method Investees                                              | 45             | 37             | 97      | 96 |   |
| Total Revenues                                                                   | 384            | 327            | 759     | 659 |   |
| DD&A                                                                         | 72             | 63             | 148     | 117 |   |
| (Gain) Loss on Divestitures                                                      | 0              | 4              | 0       | 0 |   |
| Asset Impairments                                                                | 0              | 0              | 0       | 0 |   |
| Income (Loss) from Continuing Operations Before Income Taxes                     | 204            | 268            | 465     | 499 |   |
| Total Assets                                                                     | 3,152          |           | 3,152   |   | 3,199 |
| Eastern Mediterranean [Member]                                                   |           |           |    |   |   |
| **Segment Reporting Information [Line Items]**                                   |           |           |    |   |   |
| Revenues from Third Parties                                                      | 113            | 101            | 225     | 152 |   |
| Income from Equity Method Investees                                              | 0              | 0              | 0       | 0 |   |
| Total Revenues                                                                   | 113            | 101            | 225     | 152 |   |
| DD&A                                                                         | 15             | 27             | 29      | 55 |   |
| (Gain) Loss on Divestitures                                                      | 0              | 0              | 0       | 0 |   |
| Asset Impairments                                                                | 14             | 0              | 14      | 0 |   |
| Income (Loss) from Continuing Operations Before Income Taxes                     | 44             | 44             | 121     | 59 |   |
| Total Assets                                                                     | 2,762          |           | 2,762   |   | 2,753 |
| Other Int'l & Corporate [Member]                                             |           |           |    |   |   |
| **Segment Reporting Information [Line Items]**                                   |           |           |    |   |   |
| Revenues from Third Parties                                                      | 44             | 38             | 94      | 82 |   |
| Income from Equity Method Investees                                              | 0              | 0              | 0       | 0 |   |
| Total Revenues                                                                   | 44             | 38             | 94      | 82 |   |
| DD&A                                                                         | 15             | 20             | 41      | 38 |   |
| (Gain) Loss on Divestitures                                                      | (36)           | 0              | (36)    | 0 |   |
| Asset Impairments                                                                | 2              | 0              | 94      | 0 |   |
| Income (Loss) from Continuing Operations Before Income Taxes                     | (214)          | (146)          | (458)   | (317) |   |
| Total Assets                                                                     | $ 486          |           | $ 486   |   | $ 552 |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sum of carrying amounts as of balance sheet date of all assets (with the exception of assets that are held for sale) that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or results.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of gain (loss) on sale or disposal of proven and unproven oil and gas properties.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Revenue from the sale of oil and gas during the period.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).
+ References
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| X                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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