Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Reconciliation of Unrecognized Tax Benefits
Beginning balance	$ 631		$ 565		$ 664
Tax positions taken during the current year, Increases	33		39		42
Tax positions taken during a prior year, Increases	177		102		273
Tax positions taken during a prior year, Decreases	(11)		(75)		(332)
Decreases for settlements during the period	0		0		(82)
Ending balance	812		631		565
Edison Mission Energy
Reconciliation of Unrecognized Tax Benefits
Tax positions taken during a prior year, Decreases	(18)	[1]	0	[1]	0	[1]
Southern California Edison
Reconciliation of Unrecognized Tax Benefits
Beginning balance	373		329		482
Tax positions taken during the current year, Increases	35		34		47
Tax positions taken during a prior year, Increases	169		82		140
Tax positions taken during a prior year, Decreases	(6)		(72)		(272)
Decreases for settlements during the period	0		0		(68)
Ending balance	571		373		329
Southern California Edison | Edison Mission Energy
Reconciliation of Unrecognized Tax Benefits
Tax positions taken during a prior year, Decreases	$ 0	[1]	$ 0	[1]	$ 0	[1]

[1] Unrecognized tax benefits of EME have been deconsolidated as a result of the bankruptcy filing by EME, except for tax liabilities that Edison International is jointly liable with EME under the Internal Revenue Code and applicable state statues. See Note 17 for further information.