Regulatory Assets and Liabilities (Balancing Accounts) (Details) - SCE - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Regulatory balancing and memorandum accounts | Significant components
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	$ 1,499	$ 1,388
Regulatory balancing and memorandum accounts | Portfolio allocation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	437	497
Regulatory balancing and memorandum accounts | Base revenue requirement balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	662	622
Regulatory balancing and memorandum accounts | FERC balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	12	12
Regulatory balancing and memorandum accounts | Wildfire and drought restoration accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	397	361
Regulatory balancing and memorandum accounts | Wildfire-related memorandum accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	1,142	1,104
Regulatory balancing and memorandum accounts | COVID 19-related memorandum accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	87	176
Regulatory balancing and memorandum accounts | Customer service re-platform memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	37	30
Regulatory balancing and memorandum accounts | Residential uncollectibles balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	129
Regulatory balancing and memorandum accounts | Other
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	48
Revenue subject to refund | Energy resource recovery account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	(133)	(89)
Revenue subject to refund | New system generation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	(6)	(10)
Revenue subject to refund | Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	(1,192)	(1,130)
Revenue subject to refund | Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	$ (121)	(125)
Revenue subject to refund | Other
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)		$ (60)