Regulatory Assets and Liabilities (Schedule of Net Regulatory Balancing and Memorandum Accounts) (Details) - Southern California Edison - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Regulatory balancing and memorandum accounts | Energy resource recovery account
Regulatory Assets and Liabilities
Asset (liability)	$ (355)	$ (23)
Regulatory balancing and memorandum accounts | Portfolio allocation balancing account
Regulatory Assets and Liabilities
Asset (liability)	745	537
Regulatory balancing and memorandum accounts | New system generation balancing account
Regulatory Assets and Liabilities
Asset (liability)	31	85
Refunds of excess revenue | Net regulatory balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	591	(365)
Refunds of excess revenue | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Asset (liability)	(1,322)	(1,244)
Refunds of excess revenue | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Asset (liability)	239	(328)
Refunds of excess revenue | Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Asset (liability)	(23)	(196)
Refunds of excess revenue | FERC balancing accounts
Regulatory Assets and Liabilities
Asset (liability)	32	(127)
Refunds of excess revenue | Wildfire-related memorandum accounts
Regulatory Assets and Liabilities
Asset (liability)	1,179	868
Refunds of excess revenue | COVID 19-related memorandum accounts
Regulatory Assets and Liabilities
Asset (liability)	49	0
Refunds of excess revenue | Other
Regulatory Assets and Liabilities
Asset (liability)	$ 16	$ 63