Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Current regulatory assets	$ 445	$ 350
Long-term regulatory assets	8,028	7,455
Environmental remediation
Regulatory Assets [Line Items]
Long-term regulatory assets	124	126
Southern California Edison
Regulatory Assets [Line Items]
Current regulatory assets	445	350
Long-term regulatory assets	8,028	7,455
Total regulatory assets	8,473	7,805
Southern California Edison | Regulatory balancing accounts
Regulatory Assets [Line Items]
Current regulatory assets	216	135
Long-term regulatory assets	86	66
Southern California Edison | Energy derivatives and other power contracts
Regulatory Assets [Line Items]
Current regulatory assets	203	150
Long-term regulatory assets	839	947
Southern California Edison | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Current regulatory assets	12	49
Southern California Edison | Other
Regulatory Assets [Line Items]
Current regulatory assets	14	16
Long-term regulatory assets	49	7
Southern California Edison | Deferred income taxes, net of liabilities
Regulatory Assets [Line Items]
Long-term regulatory assets	5,211	4,478
Southern California Edison | Pensions and other postretirement benefits
Regulatory Assets [Line Items]
Long-term regulatory assets	712	710
Southern California Edison | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Long-term regulatory assets	105	80
Southern California Edison | San Onofre
Regulatory Assets [Line Items]
Long-term regulatory assets	730	857
Southern California Edison | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Long-term regulatory assets	$ 172	$ 184