Summary of Significant Accounting Policies (Organization and Basis of Presentation) (Details) mi² in Thousands	9 Months Ended
Sep. 30, 2017 mi²
Southern California Edison \| Electric Utility
Segment Reporting Information [Line Items]
Supply of electricity, area covered (square mile)	50

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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