Derivative Instruments (Details 2) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Derivatives recorded on BS by location [Line Items]
Current derivative assets	$ 690	$ 725
Long-term derivative assets	134	170
Total derivative assets	824	895
Current derivative liabilities	779	718
Long-term derivative liabilities	303	370
Total derivative liabilities	1,082	1,088
Net derivative assets (liabilities)	(258)	(193)
Derivative asset fair value	824	895
Derivative liability fair value	1,082	1,088
Interest Rate Swaps
Derivatives recorded on BS by location [Line Items]
Current derivative assets
Long-term derivative assets	9	4
Total derivative assets	9	4
Current derivative liabilities	190	197
Long-term derivative liabilities	171	174
Total derivative liabilities	361	371
Net derivative assets (liabilities)	(352)	(367)
Interest Rate Swaps \| Designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value	9	2
Derivative liability fair value	140	143
Interest Rate Swaps \| Not designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value		2
Derivative liability fair value	221	228
Commodity instruments
Derivatives recorded on BS by location [Line Items]
Current derivative assets	690	725
Long-term derivative assets	125	166
Total derivative assets	815	891
Current derivative liabilities	589	521
Long-term derivative liabilities	132	196
Total derivative liabilities	721	717
Net derivative assets (liabilities)	94	174
Commodity instruments \| Designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value	98	161
Derivative liability fair value	18	52
Commodity instruments \| Not designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value	717	730
Derivative liability fair value	703	665
Designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value	107	163
Derivative liability fair value	158	195
Not designated as cash flow hedge
Derivatives recorded on BS by location [Line Items]
Derivative asset fair value	717	732
Derivative liability fair value	$ 924	$ 893

Fair values as of the balance sheet date for all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed of within a year, presented gross of master netting arrangements.

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Fair values as of the balance sheet date for all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments and which are expected to be converted into cash or otherwise disposed greater than a year, presented gross of master netting arrangements.

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Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative asset or group of derivative assets.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

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Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

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-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.

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Carrying amount as of the balance sheet date of the asset arising from derivative instruments and hedging activities, which are expected to be converted into cash or otherwise disposed of within a year or the normal operating cycle, if longer.

+ References

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+ References

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

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-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.

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Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative liability or group of derivative liabilities.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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