Compensation and Benefit Plans (Expenses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Plans
Pension and Other Postretirement Benefits
Service cost	$ 34	$ 31	$ 102	$ 93
Non-service cost (benefit)
Interest cost	26	31	78	92
Expected return on plan assets	(56)	(55)	(168)	(163)
Amortization of prior service cost				1
Amortization of net (gain) loss	3	3	9	9
Regulatory adjustment	4	2	12	6
Total non-service benefit	(23)	(19)	(69)	(55)
Total expense recognized	11	12	33	38
Postretirement Benefits Other Than Pensions
Pension and Other Postretirement Benefits
Service cost	10	10	30	28
Non-service cost (benefit)
Interest cost	14	17	42	51
Expected return on plan assets	(27)	(29)	(81)	(89)
Amortization of prior service cost		(1)		(1)
Amortization of net (gain) loss	(8)	(5)	(24)	(13)
Regulatory adjustment	11	8	33	24
Total non-service benefit	(10)	(10)	(30)	(28)
SCE
Non-service cost (benefit)
Total non-service benefit	(33)	(28)	(99)	(83)
SCE | Pension Plans
Pension and Other Postretirement Benefits
Service cost	33	31	99	91
Non-service cost (benefit)
Interest cost	24	29	72	85
Expected return on plan assets	(53)	(51)	(159)	(153)
Amortization of prior service cost				1
Amortization of net (gain) loss	2	2	6	6
Regulatory adjustment	4	2	12	6
Total non-service benefit	(23)	(18)	(69)	(55)
Total expense recognized	$ 10	$ 13	$ 30	$ 36