Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 39	$ 35
Interest cost	44	41
Expected return on plan assets	(56)	(57)
Amortization of prior service cost	1	1
Amortization of net loss	9	9
Expense under accounting standards	37	29
Regulatory adjustment	(9)	(1)
Total expense recognized	28	28
Net loss reclassified	3	3
Postretirement Benefits Other Than Pensions
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	12
Interest cost	26	29
Expected return on plan assets	(28)	(28)
Amortization of prior service cost	(1)	(3)
Amortization of net loss	0	6
Expense under accounting standards	7	16
Southern California Edison | Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	38	35
Interest cost	41	38
Expected return on plan assets	(53)	(53)
Amortization of prior service cost	1	1
Amortization of net loss	8	7
Expense under accounting standards	35	28
Regulatory adjustment	(9)	(1)
Total expense recognized	26	27
Net loss reclassified	2	2
Southern California Edison | Postretirement Benefits Other Than Pensions
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	10	12
Interest cost	26	28
Expected return on plan assets	(28)	(28)
Amortization of prior service cost	(1)	(3)
Amortization of net loss	0	6
Expense under accounting standards	$ 7	$ 15