Summary of Significant Accounting Policies (Property, Plant and Equipment and Asset Retirement Obligation) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Asset Retirement Obligation, Roll Forward
Beginning balance		$ 2,821
Ending balance		2,764	$ 2,821
Southern California Edison
Asset Retirement Obligation, Roll Forward
Beginning balance		2,819	3,418
Accretion	[1]	173	192
Revisions		(14)	(790)
Liabilities settled		(216)	(1)
Ending balance		$ 2,762	$ 2,819
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		43 years
Southern California Edison | Transmission plant
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives		52 years
Southern California Edison | General plant and other
Property, Plant and Equipment [Line Items]
Weighted-Average Useful Lives		22 years
Southern California Edison | Minimum
Property, Plant and Equipment [Line Items]
Estimated Useful Lives		5 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
Property, Plant and Equipment [Line Items]
Estimated Useful Lives		15 years
Southern California Edison | Maximum | Generation plant
Property, Plant and Equipment [Line Items]
Estimated Useful Lives		57 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.