Commitments and Contingencies (Environmental Remediation) (Details) - SCE $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) site	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 139
Environmental remediation regulatory assets	134
Expected recovery from incentive mechanism	$ 42
Expected recovery from incentive mechanism (percent)	90.00%
Recovery through customer rates	$ 92
Recovery through customer rates (percent)	100.00%
Cost may exceed recorded liability, material sites	$ 139
Cost may exceed recorded liability, immaterial sites	$ 7
Clean up (period)	30 years
Expected remediation costs for each of the next four years, low end of range	$ 6
Expected remediation costs for each of the next four years, high end of range	20
Environmental remediation expense	$ 8	$ 9	$ 4
Material sites
Jointly Owned Utility Plant Interests [Line Items]
Identified material sites (number) | site	21
Minimum estimated liability	$ 1
Recorded estimated minimum liability	135
Material sites | San Onofre
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 90
Immaterial sites
Jointly Owned Utility Plant Interests [Line Items]
Immaterial sites (number) | site	15
Immaterial sites | Minimum
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 4