Fair Value Disclosures (Estimated Fair Values Of Issued Debt And Equity Instruments) (Details) (USD $) In Millions	6 Months Ended	12 Months Ended
Jun. 30, 2011	Dec. 31, 2010
Fair Value Disclosures
Long-Term Debt, Carrying Amount	$ 3,866	$ 3,665
Long-Term Debt, Fair Value	4,317	4,045
Transition Bonds issued by ACE Funding, Carrying Amount	350	367
Transition Bonds issued by ACE Funding, Fair Value	390	406
Long-Term Project Funding, Carrying Amount	18	19
Long-Term Project Funding, Fair Value	18	19
Redeemable Serial Preferred Stock, Carrying Amount		6
Redeemable Serial Preferred Stock, Fair Value		$ 5

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 the amount of mandatorily redeemable preferred stock which the Company has issued and which is outstanding as of the balance sheet date. A financial instrument issued in the form of shares is mandatorily redeemable if it embodies an unconditional obligation requiring the issuer to redeem the instrument by transferring its assets at a specified or determinable date (or dates) or upon an event certain to occur. A financial instrument that embodies a conditional obligation to redeem the instrument by transferring assets upon an event not certain to occur becomes mandatorily redeemable - and, therefore, becomes a liability - if that event occurs, the condition is resolved, or the event becomes certain to occur. A mandatorily redeemable financial instrument shall be classified as a liability unless the redemption is required to occur only upon the liquidation or termination of the entity.

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The carrying value (book value) of an entity's issued and outstanding stock which is not included within permanent equity in Stockholders Equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer.

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