Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended			3 Months Ended	9 Months Ended			0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Jul. 08, 2013 FirstEnergy and AE Supply plant	Sep. 30, 2013 FES	Sep. 30, 2012 FES	Sep. 30, 2013 FES	Sep. 30, 2012 FES	Sep. 30, 2013 FirstEnergy and FES	Sep. 30, 2013 Operating Loss Carryforward [Member] FirstEnergy and AE Supply	Sep. 30, 2013 Operating Loss Carryforward [Member] FES	Dec. 31, 2012 Federal	Dec. 31, 2012 State and local	Jul. 09, 2013 State and local PENNSYLVANIA After December 31, 2013	Jul. 09, 2013 State and local PENNSYLVANIA After December 31, 2014
Income Taxes (Textuals) [Abstract]
Increase in unrecognized tax benefits	$ 5
Unrecognized tax benefits	4		4
Accrued interest	10		10		9
Deferred tax assets, current														319
Deferred tax assets, long-term														466	389
Deferred tax assets, portion not expected to be recognized in next fiscal year														319
Deferred tax asset, current, net operating loss carryforward	290		290
Impairment of Long-lived Assets, Number of Plants to be Deactivated						2
Valuation Allowance, Deferred Tax Asset, Change in Amount												20	4
Operating Loss Carryforward, Limitations on Use, Percent of Taxable Income																25.00%	30.00%
Operating Loss Carryforward, Limitations on Use, Amount																4	5
Valuation Allowance, Deferred Tax Asset, Change in Amount, Next Fiscal Quarter	8
Deferred Tax Liabilities, Decreases Resulting from Changes to State Apportionment Factors	9
Deferred Tax Liabilities, Decreases Resulting from Changes in Assessment of Business Operations	22
Effective tax rate	26.90%	42.10%	35.60%	41.70%			41.10%	40.50%	30.60%	39.70%	37.00%
Loss on debt redemptions	$ (9)	$ 0	$ 132	$ 0			$ 0	$ 0	$ 103	$ 0