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Other Investments (Amortized Cost and Fair Value of Nuclear Decommissioning Trusts) (Details) (Southern California Edison, USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Nuclear Decommissioning Trusts Disclosures    
Amortized Cost $ 3,074eix_DecommissioningTrustInvestmentsAmortizedCost $ 3,020eix_DecommissioningTrustInvestmentsAmortizedCost
Fair Value 4,896eix_DecommissioningTrustInvestments 4,799eix_DecommissioningTrustInvestments
Stocks
    
Nuclear Decommissioning Trusts Disclosures    
Longest Maturity Dates 0  
Amortized Cost 544eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_EquitySecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 524eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_EquitySecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Fair Value 2,074eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_EquitySecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 2,031eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_EquitySecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Municipal bonds
    
Nuclear Decommissioning Trusts Disclosures    
Longest Maturity Dates 2054  
Amortized Cost 679eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_MunicipalBondsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 681eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_MunicipalBondsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Fair Value 826eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_MunicipalBondsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 822eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_MunicipalBondsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
U.S. government and agency securities
    
Nuclear Decommissioning Trusts Disclosures    
Longest Maturity Dates 2045  
Amortized Cost 1,127eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_USGovernmentDebtSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 777eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_USGovernmentDebtSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Fair Value 1,207eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_USGovernmentDebtSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 836eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_USGovernmentDebtSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Corporate bonds
    
Nuclear Decommissioning Trusts Disclosures    
Longest Maturity Dates 2057  
Amortized Cost 585eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 346eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Fair Value 645eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 395eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_CorporateBondSecuritiesMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember
Short-term investments and receivables/payables
    
Fair Value Disclosures:    
Repurchase agreement 92us-gaap_SecuritiesPurchasedUnderAgreementsToResell
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_ShortTermInvestmentsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		  
Nuclear Decommissioning Trusts Disclosures    
Longest Maturity Dates One-year [1]  
Amortized Cost 139eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_ShortTermInvestmentsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 [1] 692eix_DecommissioningTrustInvestmentsAmortizedCost
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_ShortTermInvestmentsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 [1]
Fair Value $ 144eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_ShortTermInvestmentsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 [1] $ 715eix_DecommissioningTrustInvestments
/ eix_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisAssetTypeAxis
= us-gaap_ShortTermInvestmentsMember
/ dei_LegalEntityAxis
= eix_SouthernCaliforniaEdisonCompanyMember		 [1]
[1] Short-term investments include $92 million of repurchase agreements payable by financial institutions which earn interest, are fully secured by U.S. Treasury securities and mature by April 2, 2015.