Summary of Significant Accounting Policies (Property, Plant and Equipment) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Asset Retirement Obligation, Roll Forward
Ending balance	$ 2,782	$ 2,610
Asset retirement obligations	2,782	2,610
Southern California Edison
Property, Plant and Equipment [Line Items]
Depreciation expense stated as a percent of average original cost of depreciable utility plant (percent)	4.30%	4.30%	4.10%
Allowance for funds used during construction equity	96	96	100
Allowance for funds used during construction debt	40	42	41
Asset Retirement Obligation, Roll Forward
Beginning balance	2,610	2,507
Accretion expense	161	62
Revisions	12	42
Liabilities settled	(1)	(1)
Ending balance	2,782	2,610	2,507
Prudently incurred capital expenditure included in rate base during construction (as a percent)	100.00%
Asset retirement obligations	2,782	2,610	2,507
Southern California Edison | Generation plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	38 years
Southern California Edison | Distribution plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	37 years
Southern California Edison | Transmission plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	46 years
Southern California Edison | General and Other plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	23 years
Southern California Edison | Minimum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	12 years
Southern California Edison | Minimum | Distribution plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	30 years
Southern California Edison | Minimum | Transmission plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	35 years
Southern California Edison | Minimum | General and Other plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Southern California Edison | Maximum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	70 years
Southern California Edison | Maximum | Distribution plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	60 years
Southern California Edison | Maximum | Transmission plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	65 years
Southern California Edison | Maximum | General and Other plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	60 years
Southern California Edison | San Onofre and Palo Verde
Asset Retirement Obligation, Roll Forward
Ending balance	2,700	2,500
Asset retirement obligations	$ 2,700	$ 2,500