| **Debt (Details) (USD $)**                                                                                                                                                                                                                                                                   |                 |     | 9 Months Ended  | 12 Months Ended | 9 Months Ended       |     |                   |     | 9 Months Ended    | 12 Months Ended | 9 Months Ended    | 12 Months Ended | 9 Months Ended | 12 Months Ended | 9 Months Ended | 12 Months Ended   | 9 Months Ended    | 12 Months Ended      | 9 Months Ended       | 12 Months Ended   | 9 Months Ended    | 12 Months Ended   |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|-----|-----------------|-----------------|----------------------|-----|-------------------|-----|-------------------|-----------------|-------------------|-----------------|----------------|-----------------|----------------|-------------------|-------------------|----------------------|----------------------|-------------------|-------------------|-------------------|
||
| **Debt Instrument [Line Items]**                                                                                                                                                                                                                                                             |            |     |            |                 |                 |     |              |     |              |                 |              |            |                |            |           |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
| Debt                                                                                                                                                                                                                                                                                         | $ 4,614,000,000 |     | $ 4,123,000,000 |                 | $ 800,000,000        | [1] | $ 0               | [1] | $ 0               |                 |              | $ 328,000,000   |                | $ 330,000,000   | $ 311,000,000  | $ 200,000,000     | $ 200,000,000     | $ 1,000,000,000      | $ 1,000,000,000      | $ 1,000,000,000   | $ 1,000,000,000   | $ 100,000,000     | $ 100,000,000 | $ 250,000,000 | $ 250,000,000 | $ 850,000,000 | $ 850,000,000 | $ 84,000,000 | $ 84,000,000 |
| Interest Rate (percentage in hundredths)                                                                                                                                                                                                                                                     |            |     |            |                 | 1.36%                |     | 0.00%             |     | 0.00%             | [2]             |              | 1.79%           | [2]            | 0.00%           | 0.00%          | 5.25%             | 5.25%             | 8.25%                | 8.25%                | 4.15%             | 4.15%             | 7.25%             | 7.25% | 8.00% | 8.00% | 6.00% | 6.00% | 7.25% | 7.25% |
| Debt instrument, maturity date                                                                                                                                                                                                                                                               |            |     |            |                 | Oct.				03,				 2018 |     | Oct. 14,				 2016 |     | Sep. 30,				 2013 |                 | Sep. 30,				 2013 |            |                |            |           | Apr. 15,				 2014 | Apr. 15,				 2014 | Mar.				01,				 2019 | Mar.				01,				 2019 | Dec. 15,				 2021 | Dec. 15,				 2021 | Oct. 15,				 2023 | Oct. 15,				 2023 | Apr.				01,				 2027 | Apr.				01,				 2027 | Mar.				01,				 2041 | Mar.				01,				 2041 | Aug.				01,				 2097 | Aug.				01,				 2097 |
| Unamortized Discount                                                                                                                                                                                                                                                                         | (11,000,000)    |     | (15,000,000)    |                 |                 |     |              |     |              |                 |              |            |                |            |           |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
| Total Debt, Net of Discount                                                                                                                                                                                                                                                                  | 4,603,000,000   |     | 4,108,000,000   |                 |                 |     |              |     |              |                 |              |            |                |            |           |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
| Current Portion of Long Term Debt, net of discount                                                                                                                                                                                                                                           | 200,000,000     | [3] | 324,000,000     | [3]             |                 |     |              |     | 0                 |                 |              | (324,000,000)   |                |            |           | (200,000,000)     | 0                 |                 |                 |              |              |              |   |   |   |   |   |   |   |
| FPSO and Other Capital Lease Obligations, Current, net of discount                                                                                                                                                                                                                           |            |     |            |                 |                 |     |              |     |              |                 |              |            |                | (51,000,000)    | (48,000,000)   |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
| Long-term Debt Due After One Year                                                                                                                                                                                                                                                            | 4,352,000,000   |     | 3,736,000,000   |                 |                 |     |              |     |              |                 |              |            |                |            |           |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
| Revolving Credit Facility Maximum Borrowing Capacity                                                                                                                                                                                                                                         |            |     |            |                 | $ 4,000,000,000      |     |              |     |              |                 |              |            |                |            |           |              |              |                 |                 |              |              |              |   |   |   |   |   |   |   |
|                                                                                                                                                                                                                                                                                              |
| [1]Our Credit Agreement provides for a $4.0 billion unsecured revolving credit facility (Credit Facility), which is available for general corporate purposes.[2]Imputed rate based on the prevailing market rates for similar debt instruments at the date of assessment.[3]See Note 5. Debt |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.
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| - Definition
Interest rate stated in the contractual debt agreement.
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| - Definition
Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.
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| - Definition
Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date.
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| - Definition
Obligation related to long-term debt (excluding convertible debt) and capital leases, the portion which is due in one year or less in the future.
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| - Definition
Sum of the carrying values as of the balance sheet date of the portions of all long-term notes and loans payable due within one year or the operating cycle if longer.
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