Other Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary Of Changes In The Fair Value [Roll Forward]
Balance at beginning of period	$ 3,810	$ 3,657	$ 3,592	$ 3,480
Gross realized gains	13	46	54	81
Gross realized losses	0	(5)	(5)	(5)
Unrealized gains (losses) - net	156	(305)	272	(199)
Other-than-temporary impairments	(7)	(22)	(30)	(35)
Interest, dividends, contributions and other	25	22	114	71
Balance at end of period	$ 3,997	$ 3,393	$ 3,997	$ 3,393

Discloses the amount of interest, dividend, contribution and other receipts during the period.

No definition available.

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Period Type:	duration

- Definition

Discloses the amount of other than temporary decline in value that has been recognized by the decommissioning trust during the period.

+ References

No definition available.

+ Details

Name:	eix_DecommissioningTrustOtherThanTemporaryImpairments
Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the amount of realized gain on investments in trust during the period from the sale of securities.

+ References

No definition available.

+ Details

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Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This item represents the amount of realized loss on investments in trust during the period from the sale of securities.

+ References

No definition available.

+ Details

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Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents the amount of net unrealized gain on investments in trust during the period.

+ References

No definition available.

+ Details

Name:	eix_DecommissioningTrustUnrealizedGainsOnInvestmentsNet
Namespace Prefix:	eix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Details

Name:	eix_SummaryOfChangesInFairValueRollForward
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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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Balance Type:	debit
Period Type:	instant