Commitments and Contingencies (Contingencies Textual) (Details) (USD $)	1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended			12 Months Ended			12 Months Ended	1 Months Ended	12 Months Ended	1 Months Ended
	Jun. 30, 2010	Dec. 31, 2012 Nuclear Insurance	Dec. 31, 2012 Edison International sites	Dec. 31, 2011 Southern California Edison	Dec. 31, 2012 Southern California Edison sites	Dec. 31, 2011 Southern California Edison	Dec. 31, 2010 Southern California Edison	Sep. 15, 2012 Southern California Edison	Oct. 31, 2011 Southern California Edison Alleged violations of PSD requirements and New Source Performance Standards of the CAA private_environmental_organization	Dec. 31, 2012 Southern California Edison Nuclear Insurance	Dec. 31, 2012 SCE and other owners of San Onofre and Palo Verde Nuclear Insurance	Dec. 31, 2012 San Onofre (nuclear) Southern California Edison generator	Dec. 31, 2012 San Onofre (nuclear) Southern California Edison Outage, Inspection and Repair Issues invoices	Oct. 31, 2012 San Onofre (nuclear) Southern California Edison Outage, Inspection and Repair Issues	Dec. 31, 2005 San Onofre (nuclear) Southern California Edison Outage, Inspection and Repair Issues generator	Dec. 31, 2012 San Onofre and Palo Verde Southern California Edison Nuclear Insurance	Oct. 31, 2011 Pending Litigation Malibu Fire Order Instituting Investigation	Dec. 31, 2007 Pending Litigation Malibu Fire Order Instituting Investigation power_pole	Oct. 30, 2011 Pending Litigation Southern California Edison Malibu Fire Order Instituting Investigation
Schedule Of Commitments And Contingencies [Line Items]
Reduced power level of operation (as a percentage)														70.00%
Term of reduced power level of operation (in months)														5 months
Consecutive period of outage (months)													9 months
Required term, from notice of investigation to remove revenue requirements from customer rates (days)													45 days
Steam generators, warranted period													20 years
MHI's limited liability under purchase agreement, excluding consequential damages													$ 138,000,000
Number of invoices for reimbursement (in invoices)													3
Number of steam generators replaced (in generators)												2			4
Invoiced amount to MHI													106,000,000
Invoiced amount paid by MHI													45,000,000
Authorized expenditures													613,000,000		525,000,000
Authorized expenditures, after adjustments for inflation															665,000,000
Ownership percentage (as a percent)													78.21%
Costs incurred to date													601,000,000
Authorized expenditures by authoritative body, market costs incurred													300,000,000
Incremental inspection and repair costs													102,000,000
Incremental inspection and repair costs, payments from MHI													36,000,000
Number of failed power poles (in power poles)																		3
Damages sought				98,000,000													99,000,000		50,000,000
Number of plaintiffs (entities)									4
Identified material sites for environmental remediation (in number of sites)			23
Minimum costs to be Identified Site			1,000,000
Minimum liability for environmental remediation for material sites					103,000,000							75,000,000
Immaterial sites for environmental remediation (in number of sites)					35
Immaterial sites, range of liability, minimum					3,000,000
Environmental remediation liability					106,000,000
Regulatory assets related to environmental remediation					103,000,000
Portion of recorded liability recoverable from incentive mechanism					24,000,000
Percentage of environmental remediation costs recoverable through an incentive mechanism (as a percent)					90.00%
Liability incurred at majority of the remaining sites through customer rates					79,000,000
Environmental remediation costs to be recovered (as a percent)					100.00%
Amount that cleanup costs could exceed recorded liability for identified material sites					179,000,000
Amount that cleanup costs could exceed recorded liability for immaterial sites					7,000,000
Maximum expected period for cleanup of identified sites (in years)					30 years
Expected annual environmental remediation costs, low end of range					6,000,000
Expected annual environmental remediation costs, high end of range					13,000,000
Environmental remediation costs					10,000,000	16,000,000	17,000,000
Federal limit on public liability claims from nuclear incident, approximate		12,600,000,000
Private primary insurance purchased											375,000,000
Maximum assessment 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
Insurance coverage for wildfire liabilities Limit								550,000,000
Self insurance retention per wildfire occurrence								10,000,000
Amount of damages, decision by US Court of Federal Claims, spent nuclear fuel litigation	$ 142,000,000