Commitments and Contingencies (Environmental Remediation) (Details) - SCE $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2020 USD ($) site	Dec. 31, 2020 USD ($) site	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 259,000	$ 259,000
Environmental remediation regulatory assets	247,000	247,000
Expected recovery from incentive mechanism		$ 40,000
Expected recovery from incentive mechanism (as a percent)		90.00%
Recovery through customer rates	207,000	$ 207,000
Recovery through customer rates (as a percent)		100.00%
Alleged criminal and civil violations fine	10
Civil violations penalty	$ 3,500
Injunction period	5 years
Environmental remediation expense		$ 7,000	$ 9,000	$ 8,000
Cost may exceed recorded liability, material sites (up to)		122,000
Cost may exceed recorded liability, immaterial sites		$ 8,000
Clean up (period)		30 years
Expected remediation costs for each of the next four years, low end of range		$ 9,000
Expected remediation costs for each of the next four years, high end of range		$ 20,000
Material sites
Jointly Owned Utility Plant Interests [Line Items]
Identified material sites (number) | site	25	25
Minimum estimated liability		$ 1,000
Recorded estimated minimum liability	$ 255,000	255,000
Material sites | San Onofre
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	173,000	$ 173,000
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	4,000	$ 4,000
Mission Canyon Incident
Jointly Owned Utility Plant Interests [Line Items]
Recorded estimated minimum liability	$ 8,000	8,000
Environmental remediation expense		$ 7,000