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Other Investments (Summary of Changes in Fair Value of the Nuclear Decommissioning Trusts) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Summary Of Changes In The Fair Value [Roll Forward] |  |  |
Balance at end of period | $ 4,799 us-gaap_DecommissioningTrustAssetsAmount | $ 4,494 us-gaap_DecommissioningTrustAssetsAmount |
Southern California Edison |  |  |
Summary Of Changes In The Fair Value [Roll Forward] |  |  |
Balance at beginning of period | 4,494 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 4,048 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 3,592 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Gross realized gains | 197 eix_DecommissioningTrustRealizedGainOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 300 eix_DecommissioningTrustRealizedGainOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 73 eix_DecommissioningTrustRealizedGainOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Gross realized losses | (5)eix_DecommissioningTrustRealizedLossOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (32)eix_DecommissioningTrustRealizedLossOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (5)eix_DecommissioningTrustRealizedLossOnInvestments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Unrealized gains, net | 75 eix_DecommissioningTrustUnrealizedGainsOnInvestmentsNet / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 160 eix_DecommissioningTrustUnrealizedGainsOnInvestmentsNet / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 276 eix_DecommissioningTrustUnrealizedGainsOnInvestmentsNet / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Other-than-temporary impairments | (14)eix_DecommissioningTrustOtherThanTemporaryImpairments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (47)eix_DecommissioningTrustOtherThanTemporaryImpairments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (36)eix_DecommissioningTrustOtherThanTemporaryImpairments / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Interest, dividends and other | 118 eix_DecommissioningTrustInterestDividendsContributionsAndOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 113 eix_DecommissioningTrustInterestDividendsContributionsAndOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 113 eix_DecommissioningTrustInterestDividendsContributionsAndOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Contributions | 5 eix_DecommissioningTrustContributionsReceived / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 22 eix_DecommissioningTrustContributionsReceived / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 23 eix_DecommissioningTrustContributionsReceived / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Income taxes | (62)eix_DecommissioningTrustIncomeTaxes / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (66)eix_DecommissioningTrustIncomeTaxes / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 17 eix_DecommissioningTrustIncomeTaxes / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Decommissioning costs | (4)eix_DecommissioningTrustCosts / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 0 eix_DecommissioningTrustCosts / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | 0 eix_DecommissioningTrustCosts / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Administrative expenses and other | (5)eix_DecommissioningTrustAdministrativeExpensesandOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (4)eix_DecommissioningTrustAdministrativeExpensesandOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | (5)eix_DecommissioningTrustAdministrativeExpensesandOther / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember
Balance at end of period | $ 4,799 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | $ 4,494 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | $ 4,048 us-gaap_DecommissioningTrustAssetsAmount / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember

X
- Definition Decommissioning Trust Administrative Expenses and Other + References No definition available. + Details
Name: | eix_DecommissioningTrustAdministrativeExpensesandOther
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of contributions from customers into the decommissioning trusts. + References No definition available. + Details
Name: | eix_DecommissioningTrustContributionsReceived
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Decommissioning Trust Costs + References No definition available. + Details
Name: | eix_DecommissioningTrustCosts
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Decommissioning Trust Income Taxes + References No definition available. + Details
Name: | eix_DecommissioningTrustIncomeTaxes
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Discloses the amount of interest, dividend, contribution and other receipts during the period. + References No definition available. + Details
Name: | eix_DecommissioningTrustInterestDividendsContributionsAndOther
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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

X
- 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
Name: | eix_DecommissioningTrustRealizedGainOnInvestments
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- 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
Name: | eix_DecommissioningTrustRealizedLossOnInvestments
Namespace Prefix: | eix_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- 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
Period Type: | duration

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- Details
Name: | eix_SummaryOfChangesInFairValueRollForward
Namespace Prefix: | eix_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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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 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
Name: | us-gaap_DecommissioningTrustAssetsAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | dei_LegalEntityAxis=eix_SouthernCaliforniaEdisonCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |