Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) - SCE - USD ($)	12 Months Ended
	Dec. 31, 2018	Nov. 30, 2018	Dec. 31, 2019
Regulatory Assets and Liabilities
Wildfire insurance coverage	$ 1,000,000,000.0	$ 300,000,000
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	815,000,000		$ (23,000,000)
4% trigger amount			200,000,000
5% trigger amount			250,000,000
Regulatory balancing accounts | Portfolio allocation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	0		537,000,000
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(74,000,000)		85,000,000
Revenue subject to refund | Significant components
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(1,250,000,000)		(365,000,000)
Revenue subject to refund | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(1,200,000,000)		(1,235,000,000)
Revenue subject to refund | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(628,000,000)		(328,000,000)
Revenue subject to refund | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	28,000,000		17,000,000
Revenue subject to refund | DOE litigation memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(69,000,000)		(35,000,000)
Revenue subject to refund | Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(81,000,000)		(196,000,000)
Revenue subject to refund | FERC balancing accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	(180,000,000)		(127,000,000)
Revenue subject to refund | Wildfire expense memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	272,000,000		868,000,000
Revenue subject to refund | Other
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts	$ (133,000,000)		$ 72,000,000