Regulatory Assets and Liabilities (Schedule of Net Regulatory Balancing and Memorandum Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Regulatory balancing and memorandum accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Asset (liability)	$ (120)	$ (23)
Regulatory balancing and memorandum accounts | Portfolio allocation balancing account
Regulatory Assets and Liabilities
Asset (liability)	599	537
Regulatory balancing and memorandum accounts | New system generation balancing account
Regulatory Assets and Liabilities
Asset (liability)	75	85
Refunds of excess revenue | Net regulatory balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	17	(365)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Asset (liability)	(1,330)	(1,235)
Refunds of excess revenue | Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Asset (liability)	(7)	17
Refunds of excess revenue | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Asset (liability)	101	(328)
Refunds of excess revenue | DOE litigation memorandum account
Regulatory Assets and Liabilities
Asset (liability)	(35)	(35)
Refunds of excess revenue | Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Asset (liability)	(234)	(196)
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	(58)	(127)
Refunds of excess revenue | Wildfire-related memorandum accounts
Regulatory Assets and Liabilities
Asset (liability)	947	868
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Asset (liability)	$ 79	$ 72