Summary of Significant Accounting Policies (Property, Plant and Equipment and Asset Retirement Obligation) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Asset Retirement Obligation, Roll Forward
Ending balance	$ 2,821		$ 3,418
Southern California Edison
Asset Retirement Obligation, Roll Forward
Beginning balance	3,418		2,782
Accretion	192	[1]	182	[1]
Revisions	(790)		455
Liabilities settled	(1)		(1)
Ending balance	$ 2,819		$ 3,418
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	40 years
Southern California Edison | Transmission plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	48 years
Southern California Edison | General plant and other
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives	22 years
Southern California Edison | Minimum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	10 years
Southern California Edison | Minimum | Distribution plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	20 years
Southern California Edison | Minimum | Transmission plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	40 years
Southern California Edison | Minimum | General plant and other
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	60 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 plant and other
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	60 years

[1] An ARO represents the present value of a future obligation. Accretion is an increase in the liability to account for the time value of money resulting from discounting.