Commitments and Contingencies (Commitments) (Details) (USD $)	12 Months Ended		12 Months Ended		12 Months Ended					12 Months Ended											12 Months Ended						12 Months Ended											12 Months Ended			3 Months Ended	12 Months Ended			1 Months Ended
	Dec. 31, 2011 Homer City plant	Dec. 31, 2011 Homer City plant Senior Rent Reserve Letter of Credit	Dec. 31, 2011 Homer City plant Projected	Dec. 31, 2011 Capital Leases - Purchase Power Contracts	Dec. 31, 2011 Operating Leases Power Plants And Other	Dec. 31, 2010 Operating Leases Power Plants And Other	Dec. 31, 2009 Operating Leases Power Plants And Other	Dec. 31, 2011 Operating Leases - Power Plants	Dec. 31, 2011 Operating Leases - Other	Dec. 31, 2011 Operating Leases - Purchase Power Contracts	Dec. 31, 2010 Operating Leases - Purchase Power Contracts	Dec. 31, 2009 Operating Leases - Purchase Power Contracts	Dec. 31, 2011 Nuclear fuel supply contracts	Dec. 31, 2011 Other fuel supply contracts	Dec. 31, 2011 Coal transportation agreements		Dec. 31, 2011 Gas transportation agreements	Dec. 31, 2011 Capital expenditures	Dec. 31, 2011 Other contractual obligations	Dec. 31, 2011 Edison International	Dec. 31, 2011 Southern California Edison Company	Dec. 31, 2010 Southern California Edison Company	Dec. 31, 2009 Southern California Edison Company	Dec. 31, 2011 Southern California Edison Company Capital Leases - Purchase Power Contracts	Dec. 31, 2010 Southern California Edison Company Capital Leases - Purchase Power Contracts	Dec. 31, 2011 Southern California Edison Company Environmental Indemnities	Dec. 31, 2011 Southern California Edison Company Renewable Energy Contracts contracts	Dec. 31, 2011 Southern California Edison Company Qualifying Facility Power Purchase Agreements contracts	Dec. 31, 2011 Southern California Edison Company Other Power Purchase Agreements contracts agreements Option		Dec. 31, 2011 Edison Mission Group Inc.	Dec. 31, 2011 Edison Mission Group Inc. Transportation Purchase Commitments	Dec. 31, 2011 Edison Mission Energy Indemnities under International Asset Sale Agreements	Dec. 31, 2010 Edison Mission Energy Indemnities under International Asset Sale Agreements	Dec. 07, 2001 Other Subsidiaries of EME Homer City plant years	Aug. 24, 2000 Other Subsidiaries of EME Powerton power facilities years	Aug. 24, 2000 Other Subsidiaries of EME Joliet power facilities years	Dec. 31, 2011 Homer City	Dec. 31, 2010 Homer City	Dec. 31, 2009 Homer City	Dec. 31, 2011 Midwest Generation LLC.	Dec. 31, 2011 Midwest Generation LLC.	Dec. 31, 2010 Midwest Generation LLC.	Dec. 31, 2009 Midwest Generation LLC.	Feb. 20, 2003 Midwest Generation LLC. Environmental Indemnities under Acquisition Agreement	Dec. 31, 2011 Midwest Generation LLC. Environmental Indemnities under Acquisition Agreement cases	Dec. 31, 2010 Midwest Generation LLC. Environmental Indemnities under Acquisition Agreement
Third-Party Power Purchase Agreements
Number of renewable energy contracts																											68
Number of qualifying small power production facility contracts																												171
Number of tolling arrangements																													15
Number of power call options																													40
Number of resource adequacy contracts																													143
Undiscounted future expected payments for power purchase agreements
2012																											$ 561,000,000	$ 439,000,000	$ 624,000,000	[1]
2013																											616,000,000	438,000,000	828,000,000	[1]
2014																											712,000,000	437,000,000	812,000,000	[1]
2015																											751,000,000	426,000,000	705,000,000	[1]
2016																											752,000,000	368,000,000	476,000,000	[1]
Thereafter																											13,186,000,000	1,569,000,000	2,853,000,000	[1]
Total future commitments																											16,578,000,000	3,677,000,000	6,298,000,000	[1]
Operating leases
2012								311,000,000	99,000,000	839,000,000
2013								300,000,000	100,000,000	966,000,000
2014								289,000,000	83,000,000	930,000,000
2015								174,000,000	75,000,000	916,000,000
2016								115,000,000	65,000,000	815,000,000
Thereafter								1,412,000,000	469,000,000	11,468,000,000
Total future commitments								2,601,000,000	891,000,000	15,934,000,000
Operating lease expense					279,000,000	279,000,000	256,000,000			1,400,000,000	1,300,000,000	1,200,000,000
Carrying amount of net capital leases reflected in Utility property, plant and equipment - net on the consolidated balance sheets																								222,000,000	227,000,000
Amortization of capital leases																								27,000,000	22,000,000
Present value of the fixed capacity payments due, included in Other current liabilities																								6,000,000	5,000,000
Present value of the fixed capacity payments due included in Other deferred credits and other liabilities																								216,000,000	222,000,000
Power purchase contract, net commitments																								667,000,000
Capital leases
2012				33,000,000
2013				33,000,000
2014				72,000,000
2015				109,000,000
2016				109,000,000
Thereafter				1,751,000,000
Total future commitments				2,107,000,000
Amount representing executory costs				(445,000,000)
Amount representing interest				(773,000,000)
Net commitments				889,000,000
Sale-Leaseback Transaction
Terms of lease under sale-leaseback transaction (in years)																																			33.67	33.75	30
Senior rent service ratio	1.18		1.7
Senior rent service ratio, potential reduction	1.3
Letter of credit		48,000,000																		0	81,000,000										69,000,000
Impairment																															1,700,000,000							1,032,000,000	0	0	640,000,000	640,000,000	40,000,000	0
Nuclear Decommissioning Commitment
Estimated ARO for decommissioning all (active and inactive) nuclear facilities																					2,500,000,000
Estimated ARO for decommissioning active nuclear facilities																					2,500,000,000	2,400,000,000
Estimated cost of decommissioning through 2053																					8,600,000,000
Escalated rates, low end of the range (as a percent)																					1.80%
Escalated rates, high end of the range (as a percent)																					6.90%
Contribution received by decommissioning trust, per year																					23,000,000
Contributions received by decommissioning trust, in prior years																						23,000,000	46,000,000
Estimated annual after-tax earnings on the decommissioning funds, low end of the range (as a percent)																					4.20%
Estimated annual after-tax earnings on the decommissioning funds, high end of the range (as a percent)																					5.70%
Estimated remaining cost of decommissioning the San Onofre Unit 1 nuclear power facility, recorded as an ARO liability																					65,000,000
Total nuclear decommissioning expenditures to date, San Onofre Unit 1 project																					597,000,000
Decommissioning expense under the rate-making method																					23,000,000	30,000,000	46,000,000
Other Commitments
Purchase commitments, 2012													190,000,000	479,000,000	386,000,000	[2]	7,000,000	286,000,000	114,000,000
Purchase commitments, 2013													135,000,000	237,000,000	326,000,000	[2]	7,000,000	19,000,000	73,000,000
Purchase commitments, 2014													78,000,000	208,000,000	333,000,000	[2]	7,000,000	0	43,000,000
Purchase commitments, 2015													78,000,000	83,000,000	315,000,000	[2]	7,000,000	0	37,000,000
Purchase commitments, 2016													128,000,000	46,000,000	315,000,000	[2]	8,000,000	0	19,000,000
Remaining contract length under gas transportation agreement (in years)																																6 years
Purchase commitments, aggregate																																36,000,000
Agreement to re-sell, aggregate amount																																45,000,000
Guarantees and Indemnities
Percentage reimbursement obligation for asbestos claims (as a percent)																																													50.00%
Term of asbestos supplemental agreement																																													P5Y
Number of cases not settled and dismissed creating potential liability																																														226
Estimated liability range, minimum																					3,000,000																									46,000,000
Estimated liability range, maximum																																														64,000,000
Liability under indemnities																																	36,000,000	42,000,000												54,000,000	56,000,000
Maximum liability under indemnity per Mountainview purchase agreement for damages and other amounts																										$ 60,000,000

[1] Includes power purchase agreements with SCE's consolidated affiliates.

[2] In years 2013 through 2016, represents contracts for minimum volumes without regard to payment of alternative liquidated damages or plant closures.