Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 19, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Current regulatory assets	$ 703		$ 350
Long-term regulatory assets	4,914		7,455
SCE
Regulatory Assets [Line Items]
Current regulatory assets	703		350
Long-term regulatory assets	4,914		7,455
Total regulatory assets	5,617		7,805
SCE | Regulatory balancing accounts
Regulatory Assets [Line Items]
Current regulatory assets	484		135
Long-term regulatory assets	143		66
SCE | Power contracts and energy derivatives
Regulatory Assets [Line Items]
Current regulatory assets	203		150
Long-term regulatory assets	799		947
SCE | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Current regulatory assets	5		49
Long-term regulatory assets	123		80
SCE | Other
Regulatory Assets [Line Items]
Current regulatory assets	11		16
Long-term regulatory assets	51		7
SCE | Deferred income taxes, net of liabilities
Regulatory Assets [Line Items]
Long-term regulatory assets	3,143		4,478
SCE | Pensions and other postretirement benefits
Regulatory Assets [Line Items]
Long-term regulatory assets	271		710
SCE | San Onofre
Regulatory Assets [Line Items]
Long-term regulatory assets	72	$ 775	857
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Long-term regulatory assets	168		184
SCE | Environmental remediation
Regulatory Assets [Line Items]
Long-term regulatory assets	$ 144		$ 126