Debt and Credit Agreements (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Schedule of long-term debt
Bonds repurchased	$ (161,000,000)	$ (324,000,000)
Other long-term debt	65,000,000	117,000,000
Long-term debt due within one year	(57,000,000)	(48,000,000)
Unamortized debt discount - net	(30,000,000)	(28,000,000)
Long-term debt	13,689,000,000	12,371,000,000
Long-term debt maturities
Long-term debt maturities and sinking-fund requirements, 2012	57,000,000
Long-term debt maturities and sinking-fund requirements, 2013	755,000,000
Long-term debt maturities and sinking-fund requirements, 2014	1,500,000,000
Long-term debt maturities and sinking-fund requirements, 2015	372,000,000
Long-term debt maturities and sinking-fund requirements, 2016	966,000,000
Edison International
Schedule of long-term debt
Long-term debt	400,000,000	410,000,000
Credit Agreements and Short-Term Debt
Outstanding short-term borrowing	10,000,000	19,000,000
Commitment	1,426,000,000
Outstanding borrowings	(10,000,000)	(19,000,000)
Outstanding letters of credit	0
Amount available	1,416,000,000
Southern California Edison Company
Credit Agreements and Short-Term Debt
Outstanding short-term borrowing	419,000,000
Weighted average interest rate (as a percent)	0.44%
Commitment	2,894,000,000
Outstanding borrowings	(419,000,000)
Outstanding letters of credit	(81,000,000)
Amount available	2,394,000,000
Edison Mission Group Inc.
Credit Agreements and Short-Term Debt
Outstanding short-term borrowing	0
Commitment	1,064,000,000
Outstanding borrowings	0
Outstanding letters of credit	(69,000,000)
Amount available	995,000,000
Edison Mission Energy
Credit Agreements and Short-Term Debt
Credit facility	564,000,000
Midwest Generation LLC.
Liens and Securities Interests
Intercompany notes pledged	1,300,000,000
Net book value of assets pledged or mortgaged	2,300,000,000
Credit Agreements and Short-Term Debt
Credit facility	500,000,000
First and refunding mortgage bonds 2014-2041 (3.875% to 6.05%)
Schedule of long-term debt
Long-term debt - Gross	7,375,000,000	6,475,000,000
Interest rate on debt, low end of the range (as a percent)	3.875%
Interest rate on debt, high end of the range (as a percent)	6.05%
Pollution-control bonds 2028-2035 (2.875% to 5.0%)
Schedule of long-term debt
Long-term debt - Gross	939,000,000	1,196,000,000
Interest rate on debt, low end of the range (as a percent)	2.875%
Interest rate on debt, high end of the range (as a percent)	5.00%
Debentures and notes 2013-2053 (5.06% to 7.625%)
Schedule of long-term debt
Long-term debt - Gross	4,407,000,000	4,410,000,000
Interest rate on debt, low end of the range (as a percent)	5.06%
Interest rate on debt, high end of the range (as a percent)	7.625%
Term Loan | Tapestry Wind, LLC
Schedule of long-term debt
Long-term debt - Gross	214,000,000	0
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	2.50%
Other wind project financings
Schedule of long-term debt
Long-term debt - Gross	55,000,000	23,000,000
Letters of Credit
Line of Credit Facilities and Letters of Credit
Standby letters of credit outstanding	177,000,000
Standby letters of credit expiring in 2012	146,000,000
Standby letters of credit expiring in 2013	3,000,000
Standby letters of credit expiring in 2017	10,000,000
Standby letters of credit expiring in 2018	18,000,000
Letters of Credit | Walnut Creek Energy
Line of Credit Facilities and Letters of Credit
Standby letters of credit outstanding	40,000,000
Short-term debt | Edison International
Credit Agreements and Short-Term Debt
Weighted average interest rate (as a percent)	0.66%	0.63%
Revolving credit facilities terminating in February 2013 | Edison International
Credit Agreements and Short-Term Debt
Credit facility	1,400,000,000
Revolving credit facilities terminating in February 2013 | Southern California Edison Company
Credit Agreements and Short-Term Debt
Credit facility	2,400,000,000
Line of Credit Facilities and Letters of Credit
Termination period of credit facility (in years)	5 years
Revolving credit facilities terminating in March 2013 | Southern California Edison Company
Credit Agreements and Short-Term Debt
Credit facility	500,000,000
Line of Credit Facilities and Letters of Credit
Termination period of credit facility (in years)	3 years
Revolving credit facility | Edison International
Credit Agreements and Short-Term Debt
Credit facility	1,400,000,000
Revolving credit facility | Southern California Edison Company
Credit Agreements and Short-Term Debt
Letter of credit expiration date	twelve months or less
Senior Notes | Edison Mission Group Inc.
EMG Senior Notes
Debt, face amount	3,700,000,000
Redemption price of senior notes as a percentage of principal amount (as a percent)	100.00%
Vendor financing loan due 2014 (LIBOR plus 3.5%) | Big Sky Wind, LLC
Schedule of long-term debt
Long-term debt - Gross	211,000,000	190,000,000
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	3.50%
Term Loan Due 2020 (LIBOR plus 2.75%) | Viento Funding II, Inc.
Schedule of long-term debt
Long-term debt - Gross	207,000,000	150,000,000
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	2.75%
Construction Loan due 2013 | Walnut Creek Energy and WCEP Holdings, LLC
Schedule of long-term debt
Long-term debt - Gross	187,000,000	0
Construction Loan due 2013 | Walnut Creek Energy
Schedule of long-term debt
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	2.25%
Construction Loan due 2013 | WCEP Holdings, LLC
Schedule of long-term debt
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	4.00%
Term Loan Due 2025 (LIBOR plus 3.0%) | Cedro Hill Wind, LLC
Schedule of long-term debt
Long-term debt - Gross	131,000,000	135,000,000
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	3.00%
Term Loan due 2026 (LIBOR plus 2.75%) | Laredo Ridge
Schedule of long-term debt
Long-term debt - Gross	74,000,000	0
Floating interest rate received	LIBOR
Variable rate, spread (as a percent)	2.75%
Bonds Series 2010A and 2010B due 2017 | High Lonesome Mesa, LLC
Schedule of long-term debt
Long-term debt - Gross	$ 72,000,000	$ 75,000,000
Interest rate on debt (as a percent)	6.85%