Commitments and Contingencies (Details)		1 Months Ended				3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) site invoices	Apr. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) site invoices	Oct. 31, 2013 USD ($)	Jun. 30, 2010 USD ($)	Mar. 31, 2016 USD ($) site invoices	Dec. 31, 2012 USD ($)	Jun. 01, 2015 USD ($)
Schedule Of Commitments And Contingencies [Line Items]
Damages sought			$ 39,900,000
Gain (Loss) Related to Litigation Settlement	$ 74,500,000		74,500,000			$ 74,500,000
Nuclear Insurance
Schedule Of Commitments And Contingencies [Line Items]
Federal limit on public liability claims from nuclear incident, approximate						13,500,000,000
Southern California Edison
Schedule Of Commitments And Contingencies [Line Items]
Damages sought					$ 112,000,000
Minimum liability for environmental remediation for immaterial sites	$ 3,000,000		$ 3,000,000			$ 3,000,000
Identified material sites for environmental remediation (in number of sites) | site	19		19			19
Minimum costs to be Identified Site	$ 1,000,000
Minimum liability for environmental remediation for material sites	$ 133,000,000		$ 133,000,000			$ 133,000,000
Immaterial sites for environmental remediation (in number of sites) | site	39
Environmental remediation liability	$ 136,000,000		136,000,000			136,000,000
Regulatory assets related to environmental remediation	131,000,000		131,000,000			131,000,000
Portion of recorded liability recoverable from incentive mechanism	$ 49,000,000
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	$ 82,000,000		82,000,000			82,000,000
Environmental remediation costs to be recovered (as a percent)	100.00%
Amount that cleanup costs could exceed recorded liability for identified material sites						165,000,000
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
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						23,000,000
Environmental remediation costs						1,000,000
Insurance coverage for wildfire liabilities Limit								$ 610,000,000
Self insurance retention per wildfire occurrence								$ 10,000,000
Additional Coverage for Certain Wildfire Liabilities	$ 390,000,000		390,000,000			390,000,000
Threshold for wildfire claims (new lines for additional coverage)	610,000,000		610,000,000			610,000,000
Southern California Edison | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Minimum liability for environmental remediation for material sites	$ 80,000,000		$ 80,000,000			$ 80,000,000
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		7			7
Invoiced amount for reimbursement	$ 149,000,000		$ 149,000,000			$ 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]
Damage award		$ 124,000,000
Southern California Edison | Nuclear Insurance
Schedule Of Commitments And Contingencies [Line Items]
Limit on assessment of retrospective premium adjustments, per year, approximate						$ 45,000,000
Maximum assessment per each nuclear incident						255,000,000
Maximum yearly assessment per nuclear incident						38,000,000
Mitsubishi Heavy Industries Ltd | San Onofre
Schedule Of Commitments And Contingencies [Line Items]
Maximum liability per purchase agreement for damages	$ 138,000,000		$ 138,000,000			138,000,000
Asserted counterclaim				$ 41,000,000
SCE and other owners of San Onofre and Palo Verde
Schedule Of Commitments And Contingencies [Line Items]
Damages sought					$ 142,000,000
SCE and other owners of San Onofre and Palo Verde | Subsequent Event
Schedule Of Commitments And Contingencies [Line Items]
Damage award		$ 162,000,000
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