Commitments and Contingencies (Details)					1 Months Ended		9 Months Ended		12 Months Ended
	Oct. 26, 2015 USD ($) communication	Aug. 05, 2015 USD ($)	May. 06, 2015 USD ($)	Apr. 17, 2015 USD ($)	Oct. 31, 2015 USD ($) claims	Oct. 31, 2013 USD ($)	Sep. 30, 2015 USD ($) site invoices	Sep. 30, 2014 USD ($)	Dec. 31, 2012 USD ($)	Jun. 01, 2015 USD ($)	Aug. 31, 2014 USD ($)
Subsequent Event
Schedule Of Commitments And Contingencies [Line Items]
Number of claims | claims					2
Nuclear Insurance
Schedule Of Commitments And Contingencies [Line Items]
Federal limit on public liability claims from nuclear incident, approximate							$ 13,400,000,000
Nuclear Insurance | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Estimated settlement amount											$ 433,000,000
Nuclear Insurance | Subsequent Event | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Claims paid					$ 400,000,000
Southern California Edison
Schedule Of Commitments And Contingencies [Line Items]
Damages sought			$ 38,200,000	$ 648,000,000			182,000,000
Number of communications that should have been reported		9
Minimum damages		$ 500					$ 4,000,000
Maximum damages		$ 50,000
Identified material sites for environmental remediation (in number of sites) | site							19
Minimum costs to be Identified Site							$ 1,000,000
Minimum liability for environmental remediation for material sites							$ 137,000,000
Immaterial sites for environmental remediation (in number of sites) | site							39
Environmental remediation liability							$ 140,000,000
Regulatory assets related to environmental remediation							135,000,000
Portion of recorded liability recoverable from incentive mechanism							$ 50,000,000
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							$ 84,000,000
Environmental remediation costs to be recovered (as a percent)							100.00%
Amount that cleanup costs could exceed recorded liability for identified material sites							$ 163,000,000
Amount that cleanup costs could exceed recorded liability for immaterial sites							$ 8,000,000
Maximum expected period for cleanup of identified sites (in years)							30 years
Remediation cost estimates (period)							5 years
Expected annual environmental remediation costs, low end of range							$ 7,000,000
Expected annual environmental remediation costs, high end of range							24,000,000
Environmental remediation costs							5,000,000	$ 3,000,000
Insurance coverage for wildfire liabilities Limit							390,000,000			$ 610,000,000
Self insurance retention per wildfire occurrence										$ 10,000,000
Threshold for wildfire claims (new lines for additional coverage)							610,000,000
Southern California Edison | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Minimum liability for environmental remediation for material sites							$ 82,000,000
Southern California Edison | San Onofre | Mitsubishi Heavy Industries Ltd
Schedule Of Commitments And Contingencies [Line Items]
Damages sought						$ 4,000,000,000
Number of invoices for reimbursement | invoices							7
Invoiced amount for reimbursement							$ 149,000,000
Invoiced amount paid for reimbursement							$ 45,000,000
Share of invoice paid									$ 35,000,000
Southern California Edison | San Onofre | Mitsubishi Heavy Industries Ltd
Schedule Of Commitments And Contingencies [Line Items]
Ratepayer allocation of recovery from recoveries							50.00%
Entity allocation of recovery from recoveries							50.00%
Ratepayer allocation of recovery from recoveries, initial amount of settlement							$ 282,000,000
Southern California Edison | San Onofre | Replacement Steam Generators
Schedule Of Commitments And Contingencies [Line Items]
Warranty period							20 years
Southern California Edison | Subsequent Event
Schedule Of Commitments And Contingencies [Line Items]
Number of communications that should have been reported | communication	8
Estimated settlement amount	$ 16,740,000
Southern California Edison | Nuclear Insurance
Schedule Of Commitments And Contingencies [Line Items]
Limit on assessment of retrospective premium adjustments, per year, approximate							$ 52,000,000
Maximum assessment per each nuclear incident							255,000,000
Maximum yearly assessment per nuclear incident							38,000,000
Southern California Edison | Nuclear Insurance | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Estimated settlement amount											$ 339,000,000
Southern California Edison | Nuclear Insurance | Subsequent Event | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Claims paid					$ 313,000,000
Ratepayer allocation of recovery from recoveries					95.00%
Entity allocation of recovery from recoveries					5.00%
Mitsubishi Heavy Industries Ltd | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Maximum liability per purchase agreement for damages							138,000,000
Asserted counterclaim						$ 41,000,000
SCE and other owners of San Onofre and Palo Verde | Nuclear Insurance | San Onofre and Palo Verde
Schedule Of Commitments And Contingencies [Line Items]
Loss limit, property damage insurance, federal minimum requirement							1,060,000,000
Power Purchase Contracts | Southern California Edison
Schedule Of Commitments And Contingencies [Line Items]
2015 additional commitments							21,000,000
2016 additional commitments							142,000,000
2017 additional commitments							303,000,000
2018 additional commitments							352,000,000
2019 additional commitments							391,000,000
Additional commitments due after 2019							$ 5,200,000,000