Commitments, Guarantees and Contingencies (Details) (USD $)	3 Months Ended	6 Months Ended	12 Months Ended						6 Months Ended									1 Months Ended	6 Months Ended		1 Months Ended	6 Months Ended																						6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	May 02, 2011	Mar. 31, 2011	Jul. 11, 2011 Additional Expense Cercla	Jul. 11, 2011 Previously Reserved Cercla	Jul. 11, 2011 Cercla	Jun. 30, 2011 Nuclear Plant Matters	Mar. 28, 2011 Nuclear Plant Matters Shortfall	Jun. 24, 2011 Nuclear Plant Matters Proposed Guarantee	Jun. 30, 2011 CEI Regulation of Waste Disposal	Jun. 30, 2011 TE Regulation of Waste Disposal	Jun. 30, 2011 JCP&L Regulation of Waste Disposal	Jun. 30, 2011 Regulation of Waste Disposal	Jun. 30, 2011 Regulation of Waste Disposal FE	Jun. 30, 2011 Regulation of Waste Disposal FGCO	Dec. 31, 2010 Monongahela River Water Quality	Jun. 30, 2011 Monongahela River Water Quality	Jun. 30, 2011 Clean Water Act	Jun. 30, 2011 Climate change Tons	Jun. 30, 2011 Climate change Tons	Jun. 30, 2011 Climate change Increase in funding	Jun. 30, 2011 Climate change 2012	Jun. 30, 2011 Climate change 2025	Jun. 30, 2011 National Ambient Air Quality Standards Tons	Jun. 30, 2011 State Air Quality Compliance	Jun. 30, 2011 Caa Compliance	Jun. 30, 2011 Class Action [Member]	Jun. 30, 2011 Twenty One Individuals [Member]	Jun. 30, 2011 FES Additional Requirements	Jun. 30, 2011 Guarantees and other Assurances	Jun. 30, 2011 Guarantees and other Assurances Parental Guarantees	Jun. 30, 2011 Guarantees and other Assurances Subsidiaries Guarantees	Jun. 30, 2011 Normal Condition	Jun. 30, 2011 Normal Condition Below Investment Grade Credit Rating	Jun. 30, 2011 Normal Condition Material Adverse Event	Jun. 30, 2011 Normal Condition Acceleration of Payment	Jun. 30, 2011 Stress Condition	Jun. 30, 2011 Energy and Energy-related Activities	Jun. 30, 2011 Surety Bonds and Lines Of Credit	May 02, 2011 MP Supply	Jun. 30, 2011 FES	Jun. 30, 2011 AE Supply	May 02, 2011 AE Supply
Commitments Guarantees and Contingencies [Line Items]
Outstanding guarantees and other assurances aggregated																																$ 3,800,000,000	$ 800,000,000	$ 2,600,000,000						$ 200,000,000	$ 400,000,000
Surety bonds and related guarantees	136,000,000	136,000,000
Reduction in air emissions and compliance					81.00%
Required reduction in mercury by the beginning of 2010																											80.00%
Capping of SO2 Emissions Under CSAPR																										2,400,000
Damages for delay costs incurred									57,000,000
Outstanding collateral payments																																											138,000,000	2,000,000
Outstanding collateral payments additional requirement	49,000,000	49,000,000																													17,000,000												(93,000,000)
Signal Peak and Global Rail entered into a syndicated two-year senior secured term loan facility	350,000,000	350,000,000
Maximum exposure under collateral provisions																																			625,000,000	522,000,000	103,000,000	265,000,000	666,000,000
Number of complaints filed against FGCO																												3
Number of complaints seek enjoin plant		2																											1	1
Number of individuals behalf of which complaint filed		21
Number of named plaintiffs as class representatives		8
Number of days required prior to the filing of a citizen suit under notice																												60 days
JCP&L former owning in Keystone Station (In Percentage)																												16.67%
Capping of SO2 emissions (In Tons)																										2,500,000
Capping of NOx emissions under CSAPR																										1,200,000
Capping of NOx emissions (In Tons)																										1,300,000
Electricity production from renewable sources																								10.00%	25.00%
Upper threshold limit for carbon di oxide emission (Tons per Year)																					75,000	75,000
Total environmental liabilities												1,000,000	1,000,000	69,000,000	133,000,000	61,000,000	1,000,000
Parental guarantee associated with the funding of decommissioning costs										92,500,000	95,000,000
Percent confidence level																																											95.00%
Funds provided for Copenhagen Green Climate Fund																						30,000,000,000	100,000,000,000
Number of options proposed by EPA for additional regulation of coal combustion residuals															2
Emission allowance, current	38,000,000	38,000,000
Current value of emission allowance		40,000,000
Proposed Greenhouse Gas emissions reduction by Twenty Fifty																						80.00%
Environmental Liabilities Former Gas Facilities															63,000,000
Number of generation units																												22
Sulfate impairment designation for an approximately mile stretch of the river																		68
Number of companies received notice of complaint alleging GHG emissions																					87
Estimated clean up cost		59,000,000
Nuclear Plant Decommissioning Trusts									2,000,000,000
Number of electric generation facilities																												10
Additional expenses recognized for clean up cost	29,000,000
Previously reserved clean up cost			30,000,000
Loss incurred in damages for replacement coal purchased																																												80,000,000
Amount for replacement coal and interest				14,000,000
Number of days to appeal final judgement		30
Annual percentage that fish impingement should be reduced to, per CWA																				12.00%
Additional damages incurred for future shortfalls																																												150,000,000
Maximum Capital Investment Required To Install Technology To Meet Tds and Sulfate Limits																			150,000,000
Amount for which verdict entered for future damages																																										90,000,000			104,000,000
Estimated liability for expenses						$ 29,000,000	$ 30,000,000	$ 59,000,000