Commitments and Contingencies (Wildfires litigation) (Details) $ in Millions		1 Months Ended		2 Months Ended	3 Months Ended		12 Months Ended
	Apr. 20, 2021 plaintiff lawsuit	Jan. 31, 2021 $ / claim	Oct. 31, 2020 USD ($) $ / claim	Apr. 30, 2021 USD ($)	Mar. 31, 2021 USD ($) item	Dec. 31, 2019 USD ($)	Dec. 31, 2020 USD ($)	Jan. 31, 2019 claim
San Onofre OII
Loss Contingencies [Line Items]
Number of pending lawsuits | claim								2
2019/2020 Wildfires
Loss Contingencies [Line Items]
Charge for wildfire-related claims					$ 118
2017/2018 Wildfire/Mudslide Events
Loss Contingencies [Line Items]
Payments					620
Charge for wildfire-related claims					3,763		$ 4,383
2017/2018 Wildfire/Mudslide Events | Settled Litigation
Loss Contingencies [Line Items]
Charge for wildfire-related claims					1,800
2017/2018 Wildfire/Mudslide Events | Pending Litigation
Loss Contingencies [Line Items]
Charge for wildfire-related claims					$ 2,000
Thomas and Koenigstein Fires and Montecito Mudslides
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	37
Thomas and Koenigstein Fires, Class Action
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	4
SCE | 2017/2018 Wildfire/Mudslide Events | Local Public Entity Settlements
Loss Contingencies [Line Items]
Payments						$ 360
SCE | 2017/2018 Wildfire/Mudslide Events | TKM Subrogation Settlement
Loss Contingencies [Line Items]
Payments			$ 1,200
Payment agreement for each dollar of claim | $ / claim			0.555
SCE | 2017/2018 Wildfire/Mudslide Events | Individual Plaintiff Settlements
Loss Contingencies [Line Items]
Number of plaintiffs | item					2,000
Payments					$ 200		$ 300
SCE | Thomas and Koenigstein Fires and Montecito Mudslides
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	61
SCE | December 2017 - Thomas and Koenigstein Wildfires
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	269
Number of plaintiffs | plaintiff	3,000
SCE | November 2018 - Woolsey Wildfires
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	313
Number of plaintiffs | lawsuit	6,000
SCE | November 2018 - Woolsey Wildfires | Woolsey Subrogation Settlement
Loss Contingencies [Line Items]
Payments				$ 2,200
Payment agreement for each dollar of claim | $ / claim		0.67
SCE | Woolsey Fire, Class Action
Loss Contingencies [Line Items]
Number of pending lawsuits | lawsuit	2