Supplemental Cash Flows Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash Payments [Abstract]
Interest payments, net of capitalized interest	$ 144us-gaap_InterestPaidNet	$ 148us-gaap_InterestPaidNet	$ 137us-gaap_InterestPaidNet
Income tax payments	4us-gaap_IncomeTaxesPaid	128us-gaap_IncomeTaxesPaid	206us-gaap_IncomeTaxesPaid
Increase (Decrease) in Other Receivables	(17)	12	25
Non Cash Items Excluded From Statement of Cash Flows [Abstract]
(Increase) decrease in accrued capital expenditures	(1)	(75)	(124)
Increase in asset retirement costs	$ (56)	$ (125)	$ (8)

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(Increase) Decrease in accrued future cash outflows to pay for purchases of fixed assets that have occurred.

+ References

No definition available.

+ Details

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- Details

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

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- Definition

The increase (decrease) during the reporting period in accrued costs that represent future cash outlays for restoration and reclamation of oil and gas producing properties.

+ References

Reference 1: 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=31042434&loc=d3e3602-108585

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- Definition

The increase (decrease) during the reporting period in other amounts due to the reporting entity, which are not otherwise defined in the taxonomy.

+ References

+ Details

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- Definition

The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.

+ References

+ Details

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