Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 1,599	$ 1,121
Long-term regulatory liabilities	8,463	8,614
Southern California Edison
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,599	1,121
Long-term regulatory liabilities	8,463	8,614
Total regulatory liabilities	10,062	9,735
Southern California Edison | Regulatory balancing accounts
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,273	1,009
Long-term regulatory liabilities	1,333	1,316
Southern California Edison | Energy derivatives
Regulatory Liabilities [Line Items]
Current regulatory liabilities	41	74
Southern California Edison | Other
Regulatory Liabilities [Line Items]
Current regulatory liabilities	285	38
Long-term regulatory liabilities	36	64
Southern California Edison | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,802	2,741
Southern California Edison | Re-measurement of deferred taxes
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,796	2,892
Southern California Edison | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	1,470	1,575
Southern California Edison | Other postretirement benefits
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	$ 26	$ 26