Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Non-service cost
Total non-service cost		$ 1		$ (7)
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 32	36	$ 64	72
Non-service cost
Interest cost	35	41	70	82
Expected return on plan assets	(56)	(53)	(113)	(106)
Settlement costs	0	8	0	8
Amortization of prior service cost	0	1	1	2
Amortization of net loss	2	5	4	10
Regulatory adjustment (deferred)	3	(3)	5	(6)
Total non-service cost	(16)	(1)	(33)	(10)
Total expense recognized	16	35	31	62
Settlement costs after tax		5
Net loss reclassified	2	2	4	5
PBOP Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	9	19	18
Non-service cost
Interest cost	21	24	42	48
Expected return on plan assets	(30)	(27)	(60)	(54)
Amortization of prior service cost	(1)	(1)	(1)	(2)
Total non-service cost	(10)	(4)	(19)	(8)
Total expense	0	5	0	10
Southern California Edison
Non-service cost
Total non-service cost	(27)	(9)	(53)	(18)
Southern California Edison | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	31	35	62	70
Non-service cost
Interest cost	32	37	64	74
Expected return on plan assets	(54)	(50)	(107)	(100)
Amortization of prior service cost	0	1	1	2
Amortization of net loss	2	4	3	8
Regulatory adjustment (deferred)	3	(3)	5	(6)
Total non-service cost	(17)	(11)	(34)	(22)
Total expense recognized	14	24	28	48
Net loss reclassified	2	1	3	3
Southern California Edison | PBOP Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	10	9	19	18
Non-service cost
Interest cost	21	24	42	48
Expected return on plan assets	(30)	(27)	(60)	(54)
Amortization of prior service cost	(1)	(1)	(1)	(2)
Total non-service cost	(10)	(4)	(19)	(8)
Total expense	$ 0	$ 5	$ 0	$ 10