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Summary of Significant Accounting Policies (Property, Plant and Equipment and Asset Retirement Obligation) (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended
--- | ---
Dec. 31, 2014 | Dec. 31, 2013
Asset Retirement Obligation, Roll Forward |  |  |  |
Ending balance | $ 2,821 us-gaap_AssetRetirementObligationsNoncurrent |  | $ 3,418 us-gaap_AssetRetirementObligationsNoncurrent |
Southern California Edison |  |  |  |
Asset Retirement Obligation, Roll Forward |  |  |  |
Beginning balance | 3,418 us-gaap_AssetRetirementObligationsNoncurrent / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |  | 2,782 us-gaap_AssetRetirementObligationsNoncurrent / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |
Accretion | 192 us-gaap_AssetRetirementObligationAccretionExpense / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | [1] | 182 us-gaap_AssetRetirementObligationAccretionExpense / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember | [1]
Revisions | (790)us-gaap_AssetRetirementObligationRevisionOfEstimate / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |  | 455 us-gaap_AssetRetirementObligationRevisionOfEstimate / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |
Liabilities settled | (1)us-gaap_AssetRetirementObligationLiabilitiesSettled / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |  | (1)us-gaap_AssetRetirementObligationLiabilitiesSettled / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |
Ending balance | $ 2,819 us-gaap_AssetRetirementObligationsNoncurrent / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |  | $ 3,418 us-gaap_AssetRetirementObligationsNoncurrent / dei_LegalEntityAxis = eix_SouthernCaliforniaEdisonCompanyMember |
Southern California Edison | Generation plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Weighted-Average Useful Lives | 38 years |  |  |
Southern California Edison | Distribution plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Weighted-Average Useful Lives | 40 years |  |  |
Southern California Edison | Transmission plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Weighted-Average Useful Lives | 48 years |  |  |
Southern California Edison | General plant and other |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Weighted-Average Useful Lives | 22 years |  |  |
Southern California Edison | Minimum | Generation plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 10 years |  |  |
Southern California Edison | Minimum | Distribution plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 20 years |  |  |
Southern California Edison | Minimum | Transmission plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 40 years |  |  |
Southern California Edison | Minimum | General plant and other |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 5 years |  |  |
Southern California Edison | Maximum | Generation plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 60 years |  |  |
Southern California Edison | Maximum | Distribution plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 60 years |  |  |
Southern California Edison | Maximum | Transmission plant |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 65 years |  |  |
Southern California Edison | Maximum | General plant and other |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
Estimated Useful Lives | 60 years |  |  |
[1] | An ARO represents the present value of a future obligation. Accretion is an increase in the liability to account for the time value of money resulting from discounting.

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- Definition Weighted-average useful life of utility plant owned by the public utility. + References No definition available. + Details
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- Definition Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6392676&loc=d3e7480-110848 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of asset retirement obligations settled, or otherwise disposed of, during the period. This may include asset retirement obligations transferred to third parties associated with the sale of a long-lived asset. + 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 (c)(2) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Amount of the Increase or Decrease in the amount of the asset retirement obligation during the current period for changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation. + 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 (c)(4) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + 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 (c) -URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
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