Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Pension Plans
Pension and Other Postretirement Benefits
Service cost	$ 34	$ 31
Non-service cost
Interest cost	26	31
Expected return on plan assets	(56)	(54)
Amortization of net loss	3	3
Regulatory adjustment (deferred)	4	2
Total non-service benefit	(23)	(18)
Total expense recognized	11	13
Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Service cost	10	9
Non-service cost
Interest cost	14	17
Expected return on plan assets	(27)	(30)
Amortization of net loss	(8)	(4)
Regulatory adjustment (deferred)	11	8
Total non-service benefit	(10)	(9)
SCE
Non-service cost
Total non-service benefit	(33)	(28)
SCE | Pension Plans
Pension and Other Postretirement Benefits
Service cost	33	30
Non-service cost
Interest cost	24	28
Expected return on plan assets	(53)	(51)
Amortization of net loss	2	2
Regulatory adjustment (deferred)	4	2
Total non-service benefit	(23)	(19)
Total expense recognized	$ 10	$ 11