Compensation and Benefit Plans (Expense Components) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Postretirement Benefits Other Than Pensions
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 47	$ 40	$ 35
Interest cost	108	115	121
Expected return on plan assets	(108)	(111)	(101)
Other costs	2	0	0
Amortization of prior service cost	(35)	(35)	(36)
Amortization of net loss	39	26	35
Expense under accounting standards	53	35	54
Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	163	149	133
Interest cost	183	196	196
Expected return on plan assets	(217)	(226)	(200)
Settlement costs	5	0	0
Amortization of prior service cost	3	7	8
Amortization of net loss	61	25	20
Expense under accounting standards	198	151	157
Regulatory adjustment (deferred)	(19)	(28)	(52)
Total expense recognized	179	123	105
Southern California Edison | Postretirement Benefits Other Than Pensions
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	47	40	34
Interest cost	108	114	121
Expected return on plan assets	(109)	(111)	(100)
Other costs	2	0	0
Amortization of prior service cost	(35)	(35)	(37)
Amortization of net loss	39	26	35
Expense under accounting standards	52	34	53
Southern California Edison | Pension Plans
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	160	145	132
Interest cost	180	192	193
Expected return on plan assets	(217)	(225)	(201)
Settlement costs	4	0	0
Amortization of prior service cost	3	7	8
Amortization of net loss	57	22	17
Expense under accounting standards	187	141	149
Regulatory adjustment (deferred)	(19)	(28)	(52)
Total expense recognized	$ 168	$ 113	$ 97