v2.4.0.6

Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Price Risk Derivatives [Abstract]
Power (MWh)	(21)		(50)
Natural gas (MMBtu)	(200)		31
Interest rate swaps	$ 5,639	[1]	$ 6,171	[1]
[1] Approximately $4.1 billion and $3.3 billion at December 31, 2011 and 2010, respectively, related to variable rate debt that was converted to fixed rate debt in 2011 and 2010.

X

- Definition

Nonmonetary Notional Amount of Price Risk Derivatives Natural Gas

+ References

No definition available.

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- Definition

Aggregate notional amount of price risk derivatives for instruments with notional amounts expressed in nonmonetary units.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

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-Name Accounting Standards Codification

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- Definition

Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5580258-113959



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

-Publisher FASB

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