Commitments and Contingencies (Contingencies) (Details) (USD $)	1 Months Ended	6 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended				6 Months Ended		1 Months Ended			6 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended		6 Months Ended
	Jun. 30, 2010	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 San Onofre (nuclear)	Jun. 30, 2012 Nuclear Insurance	Oct. 31, 2011 Malibu Fire Order Instituting Investigation	Jun. 30, 2012 Edison International sites	Dec. 31, 2011 Southern California Edison Company	Jun. 30, 2012 Southern California Edison Company sites	Jun. 30, 2011 Southern California Edison Company	Sep. 01, 2011 Southern California Edison Company	Jun. 30, 2012 Southern California Edison Company San Onofre (nuclear)	Jun. 30, 2012 Southern California Edison Company Nuclear Insurance	Jun. 30, 2012 Southern California Edison Company Outage, Inspection and Repair Issues [Member] San Onofre (nuclear) H	Oct. 30, 2011 Southern California Edison Company Malibu Fire Order Instituting Investigation	Jan. 31, 2012 Midwest Generation LLC. claims	Oct. 31, 2011 Midwest Generation LLC. claims	Jun. 30, 2012 Midwest Generation LLC. sites	Aug. 31, 2009 Midwest Generation LLC. Violation of certain operating permit requirements facilities	Jun. 30, 2012 Midwest Generation LLC. Violation of certain operating permit requirements claims	Jan. 31, 2011 Homer City Violations of the PSD and Title V provisions of the CAA owners residents	Feb. 29, 2012 Homer City Alleged violations of emissions standards and limitations under the CAA and the Pennsylvania Air Pollution Control Act	Jun. 30, 2012 SCE and other owners of San Onofre and Palo Verde Nuclear Insurance
Contingencies
Number of coal-fired electric generating stations																			6
Penalties sought, per violation, per day, minimum end of range																			$ 25,000		$ 32,500
Penalties sought, per violation, per day, maximum end of range																			37,500		37,500
Number of fully dismissed claims in the complaint filed by the US EPA and the State of Illinois																				9
Number of claims in the complaint filed by the US EPA and the State of Illinois																				10
Number of complaints filed asserting claims of nuisance, negligence, trespass, and strict liability																2
Similar number of complaints previously filed asserting claims of nuisance, negligence, trespass, and strict liability that were dismissed																	2
Number of plaintiffs																					2
Number of prior owners of facilities																					2
Notice of intent to sue, notice time period																						60 days
Authorized expenditures														525,000,000
Authorized expenditures, after adjustments for inflation														665,000,000
Ownership percentage (as a percent)				78.21%
Costs incurred to date														593,000,000
Costs incurred for steam generator inspection and repair, current period														117,000,000
Collected customer rates, authorized operating costs, depreciation and return on investment														650,000,000
Rate base														1,200,000,000
Base rate, including construction work in progress														2,000,000,000
Required term, from notice of investigation to remove revenue requirements from customer rates														45 days
Continuous hours of operation, after which rates may be readjusted														100
Steam generators, warranted period														20 years
MHI's limited liability under purchase agreement, excluding consequential damages														137,000,000
Damages sought						99,000,000		98,000,000							50,000,000
Identified material sites for environmental remediation (in number of sites)							27		25									2
Identified material sites, minimum amount of upper end of range of costs							1,000,000
Minimum liability for environmental remediation							51,000,000		43,000,000			11,000,000
Amount that cleanup costs could exceed recorded liability for identified material sites									216,000,000
Amount that cleanup costs could exceed recorded liability for immaterial sites									6,000,000
Immaterial sites for environmental remediation (in number of sites)									33
Immaterial sites, range of liability, minimum									3,000,000
Environmental remediation liability									46,000,000
Percentage of environmental remediation costs recoverable through an incentive mechanism (as a percent)									90.00%
Portion of recorded liability recoverable from incentive mechanism									28,000,000
Environmental remediation costs to be recovered (as a percent)									100.00%
Liability incurred at majority of the remaining sites through customer rates									15,000,000
Regulatory assets		5,424,000,000	5,466,000,000						43,000,000
Maximum expected period for cleanup of identified sites (in years)									30 years
Expected annual environmental remediation costs, low end of range		7,000,000
Expected annual environmental remediation costs, high end of range		17,000,000
Environmental remediation costs									4,000,000	7,000,000
Federal limit on public liability claims from nuclear incident, approximate					12,600,000,000
Private primary insurance purchased																							375,000,000
Maximum deferred insurance premium per each nuclear incident													235,000,000
Maximum yearly assessment per nuclear incident													35,000,000
Loss limit, property damage insurance													500,000,000
Loss limit, property damage insurance, federal minimum requirement		1,100,000,000
Limit on assessment of retrospective premium adjustments, per year, approximate													49,000,000
Amount of damages, decision by US Court of Federal Claims, spent nuclear fuel litigation	142,000,000
Insurance Coverage for Wildfire Liabilities Limit											575,000,000
Increase In Self Insurance Retention Per Wildfire Occurence											$ 10,000,000