Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Financial Instruments [Abstract]
Increase in retained earnings for previously recognized OTTI	$ 35	$ 97
Other investments, primarily notes receivable, included in other current receivables	2	48
Special use funds: storm fund assets	125
Special use funds: nuclear decommissioning fund assets	3,742
Special use funds: nuclear decommissioning funds weighted average maturity (in years)	6 years
Special use funds: storm fund weighted average maturity (in years)	3 years
Realized gains and losses and proceeds from the sale of available for sale securities
Realized gains	183	106	108
Realized losses	88	30	30
Proceeds from sale or maturity of securities	$ 4,348	$ 6,726	$ 4,592

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- Definition

Other investments, primarily notes receivable, that are carried at estimated fair value or cost, which approximates fair value.

+ References

No definition available.

+ Details

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- Definition

Other investments, primarily notes receivable, that are carried at estimated fair value or cost, which approximates fair value. Included in other current receivables on the consolidated balance sheets.

+ References

No definition available.

+ Details

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- Definition

This item represents the weighted-average maturity of debt securities (in years) in nuclear decommissioning funds at the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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- Definition

Storm fund assets held by a regulated entity to pay for storm-related costs as incurred in future periods.

+ References

No definition available.

+ Details

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- Definition

This item represents the weighted-average maturity of debt securities (in years) held by a regulated entity in the storm fund at the balance sheet date and which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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- Definition

This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 21

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563

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- Definition

The total amount of proceeds received for the sale of securities, categorized neither as held-to-maturity nor trading securities, during the reporting period.

+ References

+ Details

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- Definition

This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

+ References

+ Details

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- Definition

The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 143

-Paragraph 22

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

+ Details

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