Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Regulatory Assets
Regulatory Assets, Current	$ 572		$ 494
Regulatory Asset, Long-term	6,422		5,466
Regulatory Liabilities
Regulatory Liabilities, Current	536		670
Regulatory Liabilities, Long-term	5,214		4,670
Southern California Edison
Regulatory Assets and Liabilities
Regulatory assets, energy derivatives, low range of contract expiration (in years)	1 year
Regulatory assets, energy derivatives, high range of contract expiration (in years)	11 years
Regulatory assets related to deferred income taxes, recovery period, low range (in years)	1 year
Regulatory assets related to deferred income taxes, recovery period, high range (in years)	45 years
Low end of the range of remaining original amortization (in years)	1 year
High end of the range of remaining original amortization (in years)	26 years
Regulatory Assets
Regulatory Assets, Current	572		494
Regulatory Asset, Long-term	6,422		5,815
Total Regulatory Assets	6,994		6,309
Regulatory Liabilities
Regulatory Liabilities, Current	536		670
Regulatory Liabilities, Long-term	5,214		4,670
Total Regulatory Liabilities	5,750		5,340
Southern California Edison | Regulatory balancing accounts
Regulatory Assets
Regulatory Assets, Current	502		223
Regulatory Asset, Long-term	73		69
Southern California Edison | Energy derivatives
Regulatory Assets
Regulatory Assets, Current	70		264
Regulatory Asset, Long-term	900	[1]	836	[1]
Southern California Edison | Other
Regulatory Assets
Regulatory Assets, Current	0		7
Regulatory Asset, Long-term	360		298
Regulatory Liabilities
Regulatory Liabilities, Current	52		9
Regulatory Liabilities, Long-term	7		4
Southern California Edison | Deferred income taxes, net
Regulatory Assets
Regulatory Asset, Long-term	2,663		2,020
Southern California Edison | Pensions and other postretirement benefits
Regulatory Assets
Regulatory Asset, Long-term	1,550		1,703
Southern California Edison | Unamortized investments, net
Regulatory Assets and Liabilities
Return rate earned on assets included in rate base (as a percent)	8.74%		8.74%
Regulatory Assets
Regulatory Asset, Long-term	507		484
Southern California Edison | Unamortized loss on reacquired debt
Regulatory Assets
Regulatory Asset, Long-term	228		249
Southern California Edison | Nuclear-related investment, net
Regulatory Assets
Regulatory Asset, Long-term	141		156
Southern California Edison | Regulatory Balancing Accounts, Liabilities
Regulatory Liabilities
Regulatory Liabilities, Current	484		661
Regulatory Liabilities, Long-term	1,091		864
Southern California Edison | Costs of Removal
Regulatory Liabilities
Regulatory Liabilities, Long-term	2,731		2,697
Southern California Edison | Asset Retirement Obligations
Regulatory Liabilities
Regulatory Liabilities, Long-term	1,385		1,105
Legacy Meters | Southern California Edison | Unamortized investments, net
Regulatory Assets and Liabilities
Return rate earned on assets included in rate base (as a percent)	6.46%
Edison Mission Energy | Southern California Edison | Energy derivatives
Regulatory Assets
Regulatory Asset, Long-term			$ 349

[1] Included in 2011 is the regulatory offset of a power purchase agreement between SCE and EME with a fair market value of $349 million, which was eliminated in the Edison International consolidated financial statements.