Available-For-Sale Securities (Fair Values And Gross Unrealized Gains And Losses For The Securities Held In The NDT Fund) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 16	$ 16
Gross Unrealized Gains	3	2
Gross Unrealized Losses	0	0
Fair Value	19	18
Total Available-For-Sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	164	158
Gross Unrealized Gains	8	2
Gross Unrealized Losses	0	0
Fair Value	172	160
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	582	525
Gross Unrealized Gains	126	213
Gross Unrealized Losses	(23)	(3)
Fair Value	685	735
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Government Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	343	301
Gross Unrealized Gains	16	6
Gross Unrealized Losses	0	(4)
Fair Value	359	303
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	268	247
Gross Unrealized Gains	15	10
Gross Unrealized Losses	(2)	(2)
Fair Value	281	255
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Debt Securities Total [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	611	548
Gross Unrealized Gains	31	16
Gross Unrealized Losses	(2)	(6)
Fair Value	640	558
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	24	70
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	24	70
Nuclear Decommissioning Trust (NDT) Fund [Member] \| Power [Member] \| Total Available-For-Sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Cost	1,217	1,143
Gross Unrealized Gains	157	229
Gross Unrealized Losses	(25)	(9)
Fair Value	$ 1,349	$ 1,363

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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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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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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