Commitments and Contingencies (Environmental Remediation) (Details) - SCE $ in Millions	9 Months Ended
	Sep. 30, 2021 USD ($) site	Sep. 30, 2020 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 261
Environmental remediation regulatory assets	246
Expected recovery from incentive mechanism	$ 39
Expected recovery from incentive mechanism (percent)	90.00%
Recovery through customer rates	$ 207
Recovery through customer rates (percent)	100.00%
Environmental remediation expense	$ 6	$ 5
Clean up (period)	30 years
Expected remediation costs, low end of range	$ 8
Expected remediation costs, high end of range	$ 24
Material sites
Jointly Owned Utility Plant Interests [Line Items]
Identified remediation sites (number) | site	26
Minimum estimated liability	$ 1
Recorded estimated minimum liability	258
Cost may exceed liability	110
Material sites | San Onofre
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 170
Immaterial sites
Jointly Owned Utility Plant Interests [Line Items]
Identified remediation sites (number) | site	14
Recorded estimated minimum liability	$ 3
Cost may exceed liability	$ 9