Debt and Credit Agreements (Details) (USD $)							1 Months Ended					1 Months Ended							1 Months Ended		1 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Southern California Edison Company Letters of Credit	Jun. 30, 2011 Edison Mission Energy Letters of Credit	Jun. 30, 2011 Letters of Credit	Jun. 30, 2011 Letters of Credit Midwest Generation LLC.	Feb. 28, 2011 Letters of Credit Viento Funding II, Inc.	Jun. 30, 2011 Edison International Short-term debt	Dec. 31, 2010 Edison International Short-term debt	Jun. 30, 2011 Southern California Edison Company Short-term debt	Jun. 30, 2011 Southern California Edison Company Revolving credit facility	Feb. 28, 2011 Term Loan due 2020 Viento Funding II, Inc.	Feb. 28, 2011 Working capital facility Viento Funding II, Inc.	May 31, 2011 Southern California Edison Company First and refunding mortgage bonds due in 2021	Jul. 31, 2011 Primary term loan Walnut Creek project	Jul. 31, 2011 Intermediate holding company loan Walnut Creek project	May 31, 2011 Southern California Edison Company Tax-exempt pollution control bonds	Jun. 30, 2011 Southern California Edison Company	Feb. 28, 2011 Viento Funding II, Inc.	Jun. 30, 2011 Viento Funding II, Inc.	Jul. 31, 2011 Walnut Creek project mW	Jul. 31, 2011 Walnut Creek project Forward swap due 2013	Jul. 31, 2011 Walnut Creek project Forward swap due 2023
Debt Instrument:
Bonds issued														$ 500,000,000
Interest rate on debt (as a percent)														3.875%
Purchase of tax-exempt bonds subject to remarketing																	56,000,000
Power generating capacity for natural gas-fired peaker plant (in megawatts)																					479
Construction loan																					495,000,000
Initial fundings of construction loan																					48,000,000
Project-level construction term loan															442,000,000	53,000,000
Period of amortizing term loan that the financing is required to be converted (in years)																					10
Letters of credit and working capital facilities																					122,000,000
Floating interest rate received															LIBOR	LIBOR			LIBOR
Variable rate, spread (as a percent)															2.25%	4.00%			2.75%
Variable rate, incremental spread after every third, sixth and ninth year (as a percent)																					0.25%
Debt, face amount							23,000,000					227,000,000	5,000,000						255,000,000
Maturity period of debt instruments (in years)							7					10	7
Long-term debt - Gross																				216,000,000
Letters of credit outstanding																		39,000,000		23,000,000
Variable rate, incremental spread (as a percent)																			0.25%
Outstanding short-term borrowing	388,000,000	115,000,000						79,000,000	19,000,000	200,000,000
Weighted average interest rate (as a percent)								0.55%	0.63%	0.33%
Credit facility											2,400,000,000
Letters of credit expiring in 12 months or less			71,000,000
Standby letters of credit outstanding				116,000,000	51,000,000	3,000,000
Standby letters of credit expiring in 2011				39,000,000	7,000,000
Standby letters of credit expiring in 2012				77,000,000	16,000,000
Standby letters of credit expiring in 2017					10,000,000
Standby letters of credit expiring in 2018					$ 18,000,000
Forward starting interest rate, low end (as a percentage)																						0.79%
Forward starting interest rate, high end (as a percentage)																						0.81%
Fixed interest rate paid (as a percent)																							3.59%