Compensation and Benefit Plans (Expense Components) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Plans
Pension and Other Postretirement Benefits
Service cost	$ 36	$ 39
Interest cost	41	44
Expected return on plan assets	(53)	(56)
Amortization of prior service cost	1	1
Amortization of net loss	5	9
Expense under accounting standards	30	37
Regulatory adjustment	(3)	(9)
Total expense recognized	27	28
Net loss reclassified	3	3
PBOP Plan
Pension and Other Postretirement Benefits
Service cost	9	10
Interest cost	24	26
Expected return on plan assets	(27)	(28)
Amortization of prior service cost	(1)	(1)
Expense under accounting standards	5	7
Southern California Edison | Pension Plans
Pension and Other Postretirement Benefits
Service cost	35	38
Interest cost	37	41
Expected return on plan assets	(50)	(53)
Amortization of prior service cost	1	1
Amortization of net loss	4	8
Expense under accounting standards	27	35
Regulatory adjustment	(3)	(9)
Total expense recognized	24	26
Net loss reclassified	2	2
Southern California Edison | PBOP Plan
Pension and Other Postretirement Benefits
Service cost	9	10
Interest cost	24	26
Expected return on plan assets	(27)	(28)
Amortization of prior service cost	(1)	(1)
Expense under accounting standards	$ 5	$ 7