Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Current regulatory assets	$ 1,314	$ 1,009
Long-term regulatory assets	7,120	6,088
SCE
Regulatory Assets [Line Items]
Current regulatory assets	1,314	1,009
Long-term regulatory assets	7,120	6,088
Total regulatory assets	8,434	7,097
SCE | Regulatory balancing and memorandum accounts
Regulatory Assets [Line Items]
Current regulatory assets	1,127	798
Long-term regulatory assets	1,794	981
SCE | Power contracts
Regulatory Assets [Line Items]
Current regulatory assets	165	189
Long-term regulatory assets	239	434
SCE | Other
Regulatory Assets [Line Items]
Current regulatory assets	22	22
Long-term regulatory assets	106	62
SCE | Deferred income taxes, net of liabilities
Regulatory Assets [Line Items]
Long-term regulatory assets	4,475	4,026
SCE | Pension and other postretirement benefits
Regulatory Assets [Line Items]
Long-term regulatory assets	12	87
SCE | Unamortized investments, net of accumulated amortization
Regulatory Assets [Line Items]
Long-term regulatory assets	114	119
SCE | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Long-term regulatory assets	133	142
SCE | Environmental remediation
Regulatory Assets [Line Items]
Long-term regulatory assets	$ 247	$ 237