Financial Instruments, Derivatives, Guarantees and Concentration of Credit Risk (Details 3) (USD $) In Millions	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009
Pre-tax gains and losses for energy commodity derivatives designated as cash flow hedges, as recognized in accumulated other comprehensive income (loss) (AOCI) or revenues
Net gain recognized in other comprehensive income (loss) (effective portion)	$ 495	$ 262
Net gain reclassified from accumulated other comprehensive income (loss) into income (effective portion)	342	618
Gain recognized in income (ineffective portion)	$ 9	$ 4

The income statement location of the effective portion of net gain or loss reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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 b
-Clause 3

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- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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- Definition

Pre-tax gains and losses for energy commodity derivatives flow hedges, as recognized in accumulated other comprehensive income (loss) (AOCI) or revenues.

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