Income Taxes (Effective Tax Rate Reconciliation) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Effective Tax Rate
Income (loss) from continuing operations before income taxes									$ (735)	$ (637)	$ (888)
Provision (benefit) for income tax at federal statutory rate of 35%									(257)	(223)	(311)
Increase (decrease) in income tax from
State tax - net of federal benefit									(32)	11	(56)
Other Tax Expense (Benefit)									(27)	0	0
Change in valuation allowance									308	438	0
Production tax credits, net									(79)	(68)	(66)
Qualified production deduction									0	0	(6)
Deferred tax adjustments									1	0	(8)
Taxes on income allocated to noncontrolling interests									(10)	(4)	0
Other									3	6	6
Provision (benefit) for income taxes from continuing operations									(93)	160	(441)
Effective tax rate (as a percent)									13.00%		50.00%
Federal statutory rate (as a percent)									35.00%	35.00%	35.00%
State tax expense (benefit)									0	0	(44)
Edison International
Increase (decrease) in income tax from
State tax expense (benefit)									5	3	6
Midwest Generation LLC [Member]
Effective Tax Rate
Income (loss) from continuing operations before income taxes									(650)	(1,526)	(442)
Provision (benefit) for income tax at federal statutory rate of 35%									(228)	(534)	(155)
Increase (decrease) in income tax from
State tax - net of federal benefit									(26)	(52)	(19)
Change in valuation allowance									234	521	0
Other									3	3	2
Provision (benefit) for income taxes from continuing operations	(17)	(1)	1	0	(23)	(7)	(27)	(5)	(17)	(62)	(172)
Effective tax rate (as a percent)									3.00%	4.00%	39.00%
Federal statutory rate (as a percent)									35.00%	35.00%	35.00%
State tax expense (benefit)									$ 0	$ 0	$ 12