Commitments, Guarantees and Contingencies (Details Textuals) (USD $)	21 Months Ended								3 Months Ended			6 Months Ended		12 Months Ended		16 Months Ended	6 Months Ended		6 Months Ended		6 Months Ended		6 Months Ended						3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended		6 Months Ended					6 Months Ended
	Dec. 05, 2011 allegation aspect_of_opinion	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 FES	Dec. 31, 2011 FES	Jun. 30, 2012 JCP&L	Dec. 31, 2011 JCP&L	Jun. 30, 2012 AE Supply	Jun. 30, 2012 Signal Peak and Global Rail	Jun. 30, 2012 FGCO	Dec. 31, 2011 FGCO	Jun. 30, 2012 CAIR phases	Jun. 30, 2012 Clean Water Act	Dec. 31, 2010 Clean Water Act mi	Apr. 30, 2009 Clean Water Act aspect_of_opinion	Feb. 27, 2007 Clean Water Act FGCO spills	Jun. 30, 2012 Regulation of Waste Disposal options	Jun. 30, 2012 Regulation of Waste Disposal JCP&L	Jun. 30, 2012 Nuclear Plant Matters	Feb. 16, 2012 Nuclear Plant Matters NuclearPowerPlants	Jun. 30, 2012 ICG Litigation AE Supply	May 02, 2011 ICG Litigation AE Supply and MP	Jun. 30, 2012 Caa Compliance ElectricGenerationUnits CoalFiredPlants	Jun. 30, 2012 Caa Compliance FGCO Complaints	Jun. 30, 2012 Caa Compliance Claim One FGCO IndividualsInAComplaint Complaints	Jun. 30, 2012 Caa Compliance Claim Two FGCO plantiffs	Jun. 30, 2012 National Ambient Air Quality Standards T	Jun. 30, 2012 National Ambient Air Quality Standards CSAPR phases	Jun. 30, 2012 Hazardous Air Pollutant Emissions MW CoalFiredPlants	Jun. 30, 2012 Hazardous Air Pollutant Emissions MW CoalFiredPlants	Jun. 30, 2012 Hazardous Air Pollutant Emissions FES	Jun. 30, 2012 Hazardous Air Pollutant Emissions FES	Mar. 08, 2012 Hazardous Air Pollutant Emissions FGCO MW	Jun. 30, 2012 Climate Change celsius	Jan. 02, 2011 Climate Change T	Jun. 30, 2012 Parental Guarantees	Jun. 30, 2012 Subsidiaries' Guarantees	Jun. 30, 2012 Other Guarantees	Jun. 30, 2012 Year 2020 Climate Change Increase in funding	Jun. 30, 2012 Regulated Distribution	Jul. 13, 2012 Plant Deactivation WEST VIRGINIA plant	Jul. 13, 2012 Plant Deactivation WEST VIRGINIA Hazardous Air Pollutant Emissions plant
Guarantor Obligations [Line Items]
Outstanding guarantees and other assurances aggregated		$ 4,100,000,000																																		$ 900,000,000	$ 2,400,000,000	$ 700,000,000
Maximum exposure under collateral provisions		804,000,000		658,000,000				73,000,000
Company Posted Collateral Related To Net Liability Positions				36,000,000																																				9,000,000
Potential Collateral Posted Related to Net Liability Positions				46,000,000				13,000,000
Signal Peak and Global Rail entered into a syndicated two-year senior secured term loan facility									350,000,000
Senior Secured Term Loan Facility, Term, Years									2 years
Number of complaints filed against FGCO																								3
Number of complaints seek enjoin plant																								2	1
Number of individuals behalf of which complaint filed																									21
Number of named plaintiffs as class representatives																										8
Reduction in air emissions and compliance																							81.00%
Number of electric generation facilities																							10
Number of generation units																							22
Number of phases under the EPA’s CAIR for reductions of Sulfur Dioxide and Mono-Nitrogen Oxides												2																2
Capping of SO2 emissions (In Tons)																											2,500,000
Capping of NOx emissions (In Tons)																											1,300,000
Capping of SO2 Emissions Under CSAPR																											2,400,000
Capping of NOx emissions under CSAPR																											1,200,000
Number of retired coal-fired plants being retired																													9	9
Megwatt Capacity for Retired Coal-Fired Power Plants																													3,349	3,349
Average percentage of power generation of retired coal-fired power plants																													10.00%	10.00%
Potential cost of compliance, MATS																													975,000,000	975,000,000
Measurement period for power generation of retired coal-fired power plants																													3 years	3 years
Commitment Period by Developed Countries to Provide Funds, Years																																		3 years
Aspects of Opinion, Reversed															1
Petroleum Spills																3
Megawatt capacity for proposed combusion turbine																																	832
Number of approved plant deactivations																																									3	3
Pre-tax severance expense related to closures																													10,000,000	17,000,000	6,000,000	10,000,000
Upper threshold limit for carbon dioxide emission (Tons per Year)																																			75,000
Increase (Decrease) in Global Temperature																																		2
Funds provided for Copenhagen Green Climate Fund																																		30,000,000,000					100,000,000,000
Annual percentage that fish impingement should be reduced to, per CWA													12.00%
Extension of comment period													30 days
Maximum Capital Investment Required To Install Technology To Meet Tds And Sulfate Limits													150,000,000
Portion of Monongahela River subject to CWA 303(d)														68
TMDL Limit Development Period													5 years
Number of days required prior to the filing of a citizen suit under notice													60 days
Claims Resolution, Civil Penalties																	800,000
Options proposed by EPA for additional regulation of coal combustion residuals																	2
Total environmental liabilities																	122,000,000	86,000,000
Environmental Liabilities Former Gas Facilities																	79,000,000
Decommissioning Fund Investments		2,153,000,000	2,112,000,000	1,250,000,000	1,223,000,000	196,000,000	193,000,000			0	0								2,000,000,000
Parental guarantee associated with the funding of decommissioning costs																			95,000,000
Request For Information from Number of Nuclear Power Plants, Total																				11
Renewal length of operating license for Davis-Besse Nuclear Power Station																			20 years
Loss incurred in damages for replacement coal purchased																					80,000,000
Additional damages incurred for future shortfalls																					150,000,000
Verdict in Favor																						104,000,000
Amount for which verdict entered for future damages																						90,000,000
Amount for replacement coal and interest																						$ 14,000,000
Potential MATS Extension Period																													1 year
Number of allegations remanded to trial court	1
Aspects of opinion under appeal	1