Available-For-Sale Securities (Fair Values And Gross Unrealized Gains And Losses For The Securities Held In The NDT Funds) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| Total Available-For-Sale Securities Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 1,216	$ 1,143
Gross Unrealized Gains	123	229
Gross Unrealized Losses	(59)	(9)
Estimated Fair Value	1,280	1,363
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| Debt Securities Total [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	613	548
Gross Unrealized Gains	30	16
Gross Unrealized Losses	(4)	(6)
Estimated Fair Value	639	558
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	273	247
Gross Unrealized Gains	14	10
Gross Unrealized Losses	(3)	(2)
Estimated Fair Value	284	255
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| US States And Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	340	301
Gross Unrealized Gains	16	6
Gross Unrealized Losses	(1)	(4)
Estimated Fair Value	355	303
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	537	525
Gross Unrealized Gains	93	213
Gross Unrealized Losses	(55)	(3)
Estimated Fair Value	575	735
Power [Member] \| Nuclear Decommissioning Trust (NDT) Funds [Member] \| Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	66	70
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	66	70
Total Available-For-Sale Securities Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	163	158
Gross Unrealized Gains	7	2
Gross Unrealized Losses	0	0
Estimated Fair Value	170	160
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	16	16
Gross Unrealized Gains	2	2
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 18	$ 18

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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