Taxes (Details) (Textuals) (USD $)	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2012 subsidiary	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 subsidiary	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes (Textuals) [Abstract]
Number of subsidiaries converted from corporations to limited liability companies (LLCs)	2
Reduction in income tax expense due to reversal of valuation allowance											$ 27,000,000
Number of unregulated subsidiaries involved in tax judgment										2
Decrease in taxable income		(253,000,000)	734,000,000	315,000,000	528,000,000	123,000,000	855,000,000	307,000,000	158,000,000
Change to FirstEnergy's earnings resulting from retiree healthcare liabilities and related tax impact already reflected in consolidated financial statements												13,000,000
Repair deduction cost												325,000,000
Reduction in effective tax rate										4,000,000	7,000,000	6,000,000
Adjustment that increased income tax expense												8,000,000
Unrecognized tax benefits	43,000,000	43,000,000				117,000,000				43,000,000	117,000,000	45,000,000	191,000,000
Unrecognized tax benefits, portion expected to be resolved in the next fiscal year	4,000,000	4,000,000								4,000,000
Previously unrecognized tax benefit, impact on effective tax rate from settlement with authorities		34,000,000								38,000,000		77,000,000
Unrecognized tax benefits, decreases resulting from settlements with taxing authorities, resulting reduction to effective tax rate		10,000,000
Recognized tax benefits											30,000,000
Tax benefits favorably affecting effective tax rate											5,000,000
Decrease in unrecognized tax benefits										7,000,000		78,000,000
Tax benefits favorably affecting effective tax rate												21,000,000
Reversal of accrued interest affecting effective tax rate												12,000,000
Deferred tax assets, gross	785,000,000	785,000,000								785,000,000
Pre-tax net operating loss carryforwards for state and local income tax purposes	15,800,000,000	15,800,000,000								15,800,000,000
Pre-tax net operating loss carryforwards expected to utilized	13,700,000,000	13,700,000,000								13,700,000,000
Federal
Income Taxes (Textuals) [Abstract]
Deferred tax assets	319,000,000	319,000,000								319,000,000
Deferred tax assets, portion not expected to be recognized in next fiscal year	274,000,000	274,000,000								274,000,000
Claim submitted for additional accelerated depreciation deductions										1,700,000,000
Number of outstanding audit issues	1	1								1
Operating loss carryforwards, not subject to expiration	25,000,000	25,000,000								25,000,000
State and Local
Income Taxes (Textuals) [Abstract]
Unrecognized tax benefits, decreases resulting from settlements with taxing authorities, resulting reduction to effective tax rate										3,000,000
Operating loss carryforwards, subject to expiration	389,000,000	389,000,000								389,000,000
New federal tax accounting method
Income Taxes (Textuals) [Abstract]
Decrease in taxable income										(417,000,000)
New federal tax accounting method | State and Local
Income Taxes (Textuals) [Abstract]
Decrease in taxable income										12,000,000
Two unregulated subsidiaries
Income Taxes (Textuals) [Abstract]
Reduction in income tax expense due to reversal of valuation allowance										(50,000,000)
FES
Income Taxes (Textuals) [Abstract]
Decrease in taxable income		(69,000,000)	169,000,000	0	198,000,000	(378,000,000)	198,000,000	39,000,000	71,000,000
Unrecognized tax benefits	3,000,000	3,000,000				45,000,000				3,000,000	45,000,000	41,000,000	41,000,000
Previously unrecognized tax benefit, impact on effective tax rate from settlement with authorities										35,000,000		2,000,000
Decrease in unrecognized tax benefits										0
FES | Federal
Income Taxes (Textuals) [Abstract]
Deferred tax assets	12,000,000	12,000,000								12,000,000
JCP&L
Income Taxes (Textuals) [Abstract]
Decrease in taxable income		(16,000,000)	139,000,000	69,000,000	48,000,000	(5,000,000)	146,000,000	77,000,000	43,000,000
Unrecognized tax benefits	0	0				0				0	0	0	14,000,000
Previously unrecognized tax benefit, impact on effective tax rate from settlement with authorities										0		(7,000,000)
Decrease in unrecognized tax benefits										0
JCP&L | Federal
Income Taxes (Textuals) [Abstract]
Deferred tax assets	1,000,000	1,000,000								1,000,000
AE Companies
Income Taxes (Textuals) [Abstract]
Previously unrecognized tax benefit, impact on effective tax rate from settlement with authorities										21,000,000
Unrecognized tax benefits, decreases resulting from settlements with taxing authorities, resulting reduction to effective tax rate		$ 7,000,000