Regulatory Assets and Liabilities (Regulatory Balancing Accounts) (Details) - SCE - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		$ 815,000,000	$ 464,000,000
Regulatory balancing accounts | New system generation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(74,000,000)	(197,000,000)
Revenue subject to refund | Significant components
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(1,250,000,000)	(1,698,000,000)
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)	(1,145,000,000)
Revenue subject to refund | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(628,000,000)	(200,000,000)
Revenue subject to refund | Tax accounting memorandum account and pole loading balancing account2
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		28,000,000	(259,000,000)
Revenue subject to refund | DOE litigation memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(69,000,000)	(156,000,000)
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)	(46,000,000)
Revenue subject to refund | Catastrophic event memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		144,000,000	102,000,000
Revenue subject to refund | Wildfire expense memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		128,000,000	0
Revenue subject to refund | FERC balancing accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(180,000,000)	(205,000,000)
Revenue subject to refund | Other
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		(133,000,000)	$ (56,000,000)
Revenue subject to refund | Tax accounting memorandum reclassified to base revenue requirement balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities) pertaining to balancing accounts		$ 263,000,000
Forecast | Regulatory balancing accounts | Energy resource recovery account
Regulatory Assets and Liabilities
4% trigger amount	$ 213,000,000
5% trigger amount	$ 266,000,000