Regulatory Assets and Liabilities (Balancing Accounts) (Details) - SCE - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Regulatory Assets and Liabilities
Environmental remediation expense	$ 6	$ 5
Significant components
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	2,018		$ 1,388
Energy resource recovery account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	348		(89)
Portfolio allocation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	98		497
New system generation balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	57		(10)
Public purpose programs and energy efficiency programs
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	(1,174)		(1,130)
Base revenue requirement balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	784		622
GRC wildfire mitigation balancing accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	48
Residential uncollectibles balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	209
Greenhouse gas auction revenue and low carbon fuel standard revenue
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	(254)		(125)
FERC balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	3		12
Wildfire and drought restoration accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	287		361
Wildfire-related memorandum accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	1,274		1,104
Revenue recognized	326
COVID 19-related memorandum accounts
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	86		176
Customer service re-platform memorandum account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	101		30
Tax accounting memorandum account and pole loading balancing account
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	204		(35)
Other
Regulatory Assets and Liabilities
Net regulatory assets (liabilities)	$ (53)		$ (25)