Compensation and Benefit Plans (Changes in Plan Assets and Benefits Obligations Recognized in OCI) (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, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Unrecognized net loss to be amortized	$ 28
Unrecognized prior service cost (credit) to be amortized	(36)
Pension Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net loss	36	13	18
Amortization of prior service cost	0	0	(1)
Amortization of net loss	(10)	(11)	(8)
Total recognized in other comprehensive loss	26	2	9
Total recognized in expense and other comprehensive income	205	125	114
Unrecognized net loss to be amortized	61
Unrecognized prior service cost (credit) to be amortized	3
Net loss to be reclassified	13
Southern California Edison | Postretirement Benefits Other Than Pensions
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Unrecognized net loss to be amortized	28
Unrecognized prior service cost (credit) to be amortized	(36)
Net loss to be reclassified	0
Southern California Edison | Pension Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net loss	20	8	15
Amortization of prior service cost	0	0	0
Amortization of net loss	(6)	(7)	(4)
Total recognized in other comprehensive loss	14	1	11
Total recognized in expense and other comprehensive income	182	114	108
Unrecognized net loss to be amortized	56
Unrecognized prior service cost (credit) to be amortized	3
Net loss to be reclassified	$ 8