Compensation and Benefit Plans (Expense and Tax Benefits of Stock Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 29	$ 29	$ 21
Income tax benefits related to stock compensation expense	4	10	6
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	15	13	11
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	5	8	1
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	8	6	7
Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1	2	2
SCE
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	13	14	11
Income tax benefits related to stock compensation expense	3	6	3
SCE | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	7	7	6
SCE | Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	2	4	1
SCE | Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4	3	4
SCE | Other
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 0	$ 0	$ 0