Acquisitions and Divestitures 2 (Details) (USD $) In Millions, unless otherwise specified		12 Months Ended
Dec. 31, 2010 Business Acquisition Dj Basin [Member]	Dec. 31, 2011 Exit from Ecuador [Member]
Business Acquisition [Line Items]
Percentage Of Working Interest Terminated		100.00%
Cash proceeds for transfer of assets		$ 73
Gain on Asset Sale		25
Total Purchase Price [Abstract]
Cash Paid	458
Net Liabilities Assumed	40
Total	498
Allocation Of Total Purchase Price [Abstract]
Proved Oil and Gas Properties	352
Unproved Oil and Gas Properties	146
Total	$ 498

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The amount of acquisition cost of a business combination allocated to proven oil and gas properties.

+ References

No definition available.

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The amount of acquisition cost of a business combination allocated to unproven oil and gas properties.

+ References

No definition available.

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- Definition

Fair Value of the liabilities incurred by the acquirer to former owners of the acquiree, including the fair value of any contingent consideration. If liabilities transferred as consideration remain within the combined entity after the business combination, and the acquirer therefore retains control of them; in that situation, the acquirer shall measure those liabilities at their carrying amounts immediately before the acquisition date.

+ References

No definition available.

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The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

+ References

No definition available.

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- Definition

Percentage of working interest in terminated by a Ecuadorian government.

+ References

No definition available.

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Amount of cash paid to acquire the entity.

+ References

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-Name Statement of Financial Accounting Standard (FAS)

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-Subparagraph f(1)

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- Definition

Gain (loss) recognized on the sale of oil and gas property or timber property.

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The cash inflow associated with the deconsolidation of a previously consolidated subsidiary or sale of an entity that is related to it but not strictly controlled.

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