Derivatives (Details 4) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Gross fair value of derivative assets and liabilities outstanding
Commodity contract derivatives asset, cash flow hedges	$ 29	$ 60
Commodity contract derivatives asset not designated as hedging instruments	1,060	915
Commodity contract derivatives asset, gross	1,089	975
Commodity contract derivatives liability, cash flow hedges	113	209
Commodity contract derivatives liability not designated as hedging instruments	1,028	908
Commodity contract derivative liability, gross	1,141	1,117
Less: counterparty netting and cash collateral, asset	(801)	(680)
Less: counterparty netting and cash collateral, liability	(830)	(736)
Total net fair value, asset	288	295
Total net fair value, liability	311	381
Payables in respect of cash collateral received netted with derivative assets	45	39
Receivables in respect of cash collateral paid netted with derivative liabilities	74	95
Collateral deposited with clearing houses and brokers	64	154
Net derivative liabilities with credit-risk-related contingent features	66	234
Amount of collateral posted	35	10
Marketing and trading assets and other
Gross fair value of derivative assets and liabilities outstanding
Commodity contract derivatives asset, cash flow hedges	29	51
Commodity contract derivatives asset not designated as hedging instruments	999	829
Long-term receivables and other assets, net
Gross fair value of derivative assets and liabilities outstanding
Commodity contract derivatives asset, cash flow hedges		9
Commodity contract derivatives asset not designated as hedging instruments	61	86
Accrued liabilities
Gross fair value of derivative assets and liabilities outstanding
Commodity contract derivatives liability, cash flow hedges	113	209
Commodity contract derivatives liability not designated as hedging instruments	968	823
Deferred credits and other liabilities
Gross fair value of derivative assets and liabilities outstanding
Commodity contract derivatives liability not designated as hedging instruments	$ 60	$ 85

Amount of collateral deposited with clearing houses and brokers that has not been offset against derivative fair values.

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The amount as of the balance sheet date of the fair value of derivative assets after counterparty netting and offsetting of cash collateral when a legal right to offset exists.

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The amount as of the balance sheet date of the fair value of derivative assets that was offset by counterparty netting and cash collateral when a legal right to offset exists.

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- Definition

The amount as of the balance sheet date of the fair value of derivative liabilities that was offset by counterparty netting and cash collateral when a legal right to offset exists.

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- Definition

The amount as of the balance sheet date of the fair value of derivative liabilities after counterparty netting and offsetting of cash collateral when a legal right to offset exists.

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The amount of payables in respect of cash collateral received that has been netted with derivative assets.

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The amount of receivables in respect of cash collateral paid that has been netted with derivative liabilities.

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- Definition

The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44D
-Subparagraph c

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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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 205G

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44C
-Subparagraph a
-Clause 1

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Fair value of derivative liability, 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

+ Details

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The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain or loss on that instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 44D
-Subparagraph b

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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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Fair value as of the balance sheet date of all price risk derivative assets designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 17

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Fair value as of the balance sheet date of all price risk derivative liabilities designated as cash flow hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 17

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Fair value as of the balance sheet date of all price risk derivative assets not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 17

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Fair value as of the balance sheet date of all price risk derivative liabilities not designated as hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 17

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