Derivative Instruments and Hedging Activities (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Asset Derivative Instruments	$ 17	$ 84
Liability Derivative Instruments	75	10
Realized Mark-to-Market (Gain) Loss	2	34	(64)
Unrealized Mark-to-Market (Gain) Loss	131	(109)	22
Total (Gain) Loss on Commodity Derivative Instruments	133	(75)	(42)
Current Assets
Derivatives, Fair Value [Line Items]
Asset Derivative Instruments	1	63
Current Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivative Instruments	65	7
Noncurrent Assets
Derivatives, Fair Value [Line Items]
Asset Derivative Instruments	16	21
Noncurrent Liabilities
Derivatives, Fair Value [Line Items]
Liability Derivative Instruments	10	3
Crude Oil Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Realized Mark-to-Market (Gain) Loss	52	83	44
Unrealized Mark-to-Market (Gain) Loss	87	(120)	5
Natural Gas Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Realized Mark-to-Market (Gain) Loss	(50)	(49)	(108)
Unrealized Mark-to-Market (Gain) Loss	$ 44	$ 11	$ 17

Fair value before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

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-Subparagraph (a),(c)

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Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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- Definition

Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

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The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

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

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-Name Accounting Standards Codification

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-Subparagraph (SX 210.9-04.13(h))

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The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of open derivatives, commodity, or energy contracts, held at each balance sheet date, that was included in earnings for the period.

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