Variable Interest Entities (Variable Interest in VIEs that are not Consolidated) (Details)	1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($) MW	Dec. 31, 2019 USD ($) MW	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($) $ / shares
Unconsolidated Trust
Redemption of preferred and preference stock			$ 308,000,000
SCE
Unconsolidated Trust
Redemption of preferred and preference stock		$ 120,000,000	$ 308,000,000
SCE | 5.10% Series G (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)			5.10%
SCE | 5.75% Series H (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)			5.75%
SCE | 5.375% Series J (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)			5.375%
SCE | 5.45% Series K (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)			5.45%
SCE | 5.00% Series L (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)			5.00%
SCE | VIE | Power Purchase Agreements
Details of projects or entities
Power generating capacity for majority interest (in megawatts) | MW			5,103	4,497
Payments to unconsolidated VIEs for power purchase contracts			$ 744,000,000	$ 833,000,000
SCE | VIE | Trust II | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)									5.10%
Liquidation preference			220,000,000	400,000,000					$ 400,000,000
Liquidation value (in dollars per share) | $ / shares									$ 25
Common stock									$ 10,000
SCE | VIE | Trust II | 5.10% Series G (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)									5.10%
Liquidation preference			220,000,000	400,000,000					$ 400,000,000
Liquidation value (in dollars per share) | $ / shares									$ 2,500
Redemption of preferred and preference stock	$ 180,000,000
SCE | VIE | Trust III | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)								5.75%
Liquidation preference			275,000,000	275,000,000				$ 275,000,000
Liquidation value (in dollars per share) | $ / shares								$ 25
Common stock								$ 10,000
Redemption of preferred and preference stock			10,000	10,000
SCE | VIE | Trust III | 5.75% Series H (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)								5.75%
Liquidation preference			275,000,000	275,000,000				$ 275,000,000
Liquidation value (in dollars per share) | $ / shares								$ 2,500
SCE | VIE | Trust IV | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)							5.375%
Liquidation preference			325,000,000	325,000,000			$ 325,000,000
Liquidation value (in dollars per share) | $ / shares							$ 25
Common stock							$ 10,000
Redemption of preferred and preference stock			10,000	10,000
SCE | VIE | Trust IV | 5.375% Series J (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)							5.375%
Liquidation preference			325,000,000	325,000,000			$ 325,000,000
Liquidation value (in dollars per share) | $ / shares							$ 2,500
SCE | VIE | Trust V | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)						5.45%
Liquidation preference			300,000,000	300,000,000		$ 300,000,000
Liquidation value (in dollars per share) | $ / shares						$ 25
Common stock						$ 10,000
Redemption of preferred and preference stock			10,000	10,000
SCE | VIE | Trust V | 5.45% Series K (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)						5.45%
Liquidation preference			300,000,000	300,000,000		$ 300,000,000
Liquidation value (in dollars per share) | $ / shares						$ 2,500
SCE | VIE | Trust VI | Trust Securities
Unconsolidated Trust
Security dividend rate, (as a percent)					5.00%
Liquidation preference			475,000,000	475,000,000	$ 475,000,000
Liquidation value (in dollars per share) | $ / shares					$ 25
Common stock					$ 10,000
Redemption of preferred and preference stock			10,000	10,000
SCE | VIE | Trust VI | 5.00% Series L (cumulative)
Unconsolidated Trust
Security dividend rate, (as a percent)					5.00%
Liquidation preference			$ 475,000,000	$ 475,000,000	$ 475,000,000
Liquidation value (in dollars per share) | $ / shares					$ 2,500