Summary of Significant Accounting Policies Asset Retirement Obligation (Details) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2014		Dec. 31, 2013		Jun. 30, 2014
Significant Accounting Policies [Line Items]
Decommissioning Costs, Future Value					$ 4,400,000,000
Asset Retirement Obligation, Discount Rate (percent)	6.30%
Southern California Edison
Significant Accounting Policies [Line Items]
Decommissioning Costs, Future Value					3,300,000,000
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	3,418,000,000		2,782,000,000
Accretion1	150,000,000	[1]	182,000,000	[1]
Revisions	(604,000,000)		455,000,000
Liabilities settled	(4,000,000)		(1,000,000)
Ending balance	2,960,000,000		3,418,000,000
Southern California Edison | San Onofre
Significant Accounting Policies [Line Items]
Asset Retirement Obligation, Discount Rate (percent)	6.30%
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Beginning balance	2,700,000,000
Revisions	604,000,000
Ending balance	$ 2,200,000,000

[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.