| **Additional Financial Statement Information (Details 2) (USD $)In Millions, unless otherwise specified** | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------|-----------------|
||
| **Cash Paid During the Year For [Abstract]**                                                              |            |   |  |   |  |
| Interest, Net of Amount Capitalized                                                                       | $ 137           | $ 107 |  | $ 32 |  |
| Income Taxes Paid, Net                                                                                    | 165             | 168 |  | 288 |  |
| **Non-Cash Financing and Investing Activities [Abstract]**                                                |            |   |  |   |  |
| Increase in CONSOL Installment Payments, Net of Discount                                                  | 0               | 0 | [1] | 639 |  |
| Increase in FPSO Lease Obligation                                                                         | $ 96            | $ 0 | [1] | $ 66 | [1] |
|                                                                                                           |
| [1]See Note 3. Property Transactions and Note 10. Long-Term Debt.                                         |

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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The increase during the period in capital lease obligations due to entering into new capital leases.
+ References
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| - Definition
The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.
+ References
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The net book value of a nonmonetary asset transferred or exchanged in connection with the acquisition of a business or asset in a noncash transaction. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. Nonmonetary assets and liabilities are assets and liabilities that will not result in cash receipts or cash payments in the future.
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