| **Allowance for Doubtful Accounts (Details) (USD $)In Millions, unless otherwise specified**                                                                                                                                                                                         | 12 Months Ended |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Allowance for Doubtful Accounts [Abstract]**                                                                                                                                                                                                                                       |            |   |  |   |
| Recovery of Ecuador Receivable                                                                                                                                                                                                                                                       | $ 0             | $ 19 | [1] | $ 6 |
| **Allowance for doubtful accounts [Rollforward]**                                                                                                                                                                                                                                    |            |   |  |   |
| Balance, Beginning of Period                                                                                                                                                                                                                                                         | 9               | 27 |  | 31 |
| Changes in Ecuador Receivables, Net                                                                                                                                                                                                                                                  | 0               | (19) | [1] | (6) |
| Other Changes                                                                                                                                                                                                                                                                        | 1               | 1 |  | 2 |
| Net Changes                                                                                                                                                                                                                                                                          | 1               | (18) |  | (4) |
| Balance, End of Period                                                                                                                                                                                                                                                               | $ 10            | $ 9 |  | $ 27 |
|                                                                                                                                                                                                                                                                                      |
| [1]During 2011, recovery of approximately $19 million for outstanding receivables was included in the final terms of our agreement to transfer our assets and the associated electricity concession and PSC to the Ecuadorian government. See Note 3. Acquisitions and Divestitures. |

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| - Definition
For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.
+ References
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| - Definition
Amount of increase (decrease) in the allowance for doubtful accounts.
+ References
No definition available.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of recoveries of receivables doubtful of collection that were previously charged off.
+ References
No definition available.
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| - Definition
Amount of the current period expense charged against operations, the offset which is generally to the allowance for doubtful accounts for the purpose of reducing receivables, including notes receivable, to an amount that approximates their net realizable value (the amount expected to be collected).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 5 -Article 5Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.5) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688
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