Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Current regulatory liabilities	$ 1,341	$ 1,121
Long-term regulatory liabilities	8,659	8,614
Southern California Edison
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,341	1,121
Long-term regulatory liabilities	8,659	8,614
Total regulatory liabilities	10,000	9,735
Southern California Edison | Regulatory balancing accounts
Regulatory Liabilities [Line Items]
Current regulatory liabilities	1,004	1,009
Long-term regulatory liabilities	1,539	1,316
Southern California Edison | Energy derivatives
Regulatory Liabilities [Line Items]
Current regulatory liabilities	50	74
Southern California Edison | San Onofre
Regulatory Liabilities [Line Items]
Current regulatory liabilities	96	5
Long-term regulatory liabilities	26	26
Southern California Edison | Other
Regulatory Liabilities [Line Items]
Current regulatory liabilities	191	33
Long-term regulatory liabilities	37	64
Southern California Edison | Costs of removal
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,804	2,741
Southern California Edison | Re-measurement of deferred taxes
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	2,815	2,892
Southern California Edison | Recoveries in excess of ARO liabilities
Regulatory Liabilities [Line Items]
Long-term regulatory liabilities	$ 1,438	$ 1,575