Risk Management and Fair Values (Details Textuals) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Risk Management and Fair Values (Textuals) [Abstract]
Cash flow hedges relating to power sales as part of net gains			$ 90
Reclassified from accumulated other comprehensive income (OCI) to operating revenues			96
Amount of gain reclassified from accumulated OCI into income (effective portion)	32	67	61	103
Maturity of cash flow hedges, Tax	11	23	21	36
Maximum length of time over which Company is currently hedging the variability in future cash flows for forecasted power transactions	approximately 3.5 years		approximately 3.5 years
Planned generation sold forward from Wholesale Commodities	96.00%		96.00%
Planned Generation Sold Forward under financial derivatives	46.00%		46.00%
Dollar amount of hedge contract in a liability position	9		9
Total volume of natural gas swaps outstanding (MMBtu)	31,620,000		31,620,000
Cash flow hedges in-the-money contracts	107		107
Cash flow hedges out-of-the-money contracts	$ 9		$ 9
Average coupon rate of debt securities	4.23%		4.23%

Average Coupon Rate Of Debt Securities Percentage.

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- Definition

Cash flow hedges money contracts.

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Cash flow hedges out-of-the-money contracts.

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- Definition

Derivative Instruments Gain Loss Reclassified From Accumulated OCI Into Income Effective Portion, Tax.

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Dollar amount of hedge contract in a liability position.

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- Definition

Maximum length of time over which Company is currently hedging the variability in future cash flows with derivatives for forecasted power transactions.

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- Definition

Planned Generation From Non Nuclear Power Plants Sold Forward Under Financial Hedges

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Planned Generation Sold Forward From Wholesale Commodities.

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Risk Management and Fair Values Textuals Abstract.

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Total volume of natural gas swaps outstanding.

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- Definition

The estimated net amount of existing gains (losses) on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph b(2)

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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.

+ 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 b
-Clause 3

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Amount of unrealized gain (loss) related to derivatives designated as cash flow hedging instruments, recorded in results of operations to the extent that the cash flow hedge is determined to be ineffective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 45
-Subparagraph b(1)

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