Discontinued Operations (Details 1) (Segment, Discontinued Operations [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
Segment, Discontinued Operations [Member]
Pre Tax Gains And Losses For Energy Commodity Derivatives Designated As Cash Flow Hedges [Abstract]
Net gain (loss) recognized in other comprehensive income (loss) (effective portion)	$ 413
Net gain (loss) reclassified from accumulated other comprehensive income (loss) into income (effective portion)	332
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net Abstract
Gain (loss) recognized in income	$ 30

The effective portion of net gain (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 Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4D

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624177-113959

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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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Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments.

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