Debt and Credit Agreements (Details) (USD $) In Millions, unless otherwise specified									3 Months Ended		1 Months Ended	3 Months Ended		3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Edison International	Dec. 31, 2011 Edison International	Mar. 31, 2012 Southern California Edison Company	Dec. 31, 2011 Southern California Edison Company	Mar. 31, 2012 Edison Mission Energy	Feb. 29, 2012 Edison Mission Energy	Mar. 31, 2012 Broken Bow and Crofton Bluffs Wind Projects	Mar. 31, 2012 First and refunding mortgage bonds Southern California Edison Company	Dec. 31, 2011 Term Loan Tapestry Wind, LLC	Mar. 31, 2012 Term Loan Tapestry Wind, LLC	Mar. 31, 2012 Letters of Credit	Mar. 31, 2012 Letters of Credit Southern California Edison Company	Mar. 31, 2012 Letters of Credit Edison Mission Energy	Mar. 31, 2012 Letters of Credit Walnut Creek credit facility	Mar. 31, 2012 Revolving credit facility Southern California Edison Company	Feb. 29, 2012 Revolving credit facility Edison Mission Energy	Mar. 31, 2012 Revolving credit facility terminating June 2014 Edison Mission Energy
Debt Instrument:
Construction loans									$ 79
Long-term debt - Gross										400	214
Term of amortizing loan (in years)									15 years			10 years
Letter of credit facilities								55	13
Working capital facilities									6
Floating interest rate received									LIBOR
Variable rate, spread (as a percent)									2.875%
Variable rate, increase rate after third, sixth, ninth and twelfth years (as a percent)									0.125%
Interest rate on debt (as a percent)										4.05%
Cash proceeds received from issuance of debt											97
Outstanding credit facility														63
Outstanding short-term debt	343	429	13	10	330	419
Short-term debt, weighted average interest rate (as a percent)			0.87%	0.66%	0.40%	0.44%
Credit facility			1,400														2,300	564	100
Letter of credit expiration date														twelve months or less
Standby letters of credit outstanding													179			40
Standby letters of credit expiring in 2012													122
Standby letters of credit expiring in 2013													29
Standby letters of credit expiring in 2017													10
Standby letters of credit expiring in 2018													18
Outstanding letters of credit							71
Cash collateral															$ 74