Commitments, Guarantees and Contingencies (Details Textuals) (USD $)	3 Months Ended							3 Months Ended			3 Months Ended			12 Months Ended	3 Months Ended		3 Months Ended		3 Months Ended		3 Months Ended						3 Months Ended					3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 FES	Dec. 31, 2011 FES	Mar. 31, 2012 JCP&L	Dec. 31, 2011 JCP&L	Mar. 31, 2012 AE Supply	Mar. 31, 2012 Signal Peak and Global Rail	Mar. 31, 2012 FGCO	Dec. 31, 2011 FGCO	Mar. 31, 2012 CAIR phases	Mar. 31, 2012 CSAPR phases	Mar. 31, 2012 Clean Water Act	Dec. 31, 2010 Clean Water Act Miles	Mar. 31, 2012 Regulation of Waste Disposal options	Mar. 31, 2012 Regulation of Waste Disposal JCP&L	Mar. 31, 2012 Nuclear Plant Matters	Dec. 31, 2011 Nuclear Plant Matters	Mar. 31, 2012 ICG Litigation AE Supply	May 02, 2011 ICG Litigation AE Supply and MP	Mar. 31, 2012 Caa Compliance ElectricGenerationUnits CoalFiredPlants	Mar. 31, 2012 Caa Compliance FGCO Complaints plantiffs IndividualsInAComplaint	Mar. 31, 2012 National Ambient Air Quality Standards T	Mar. 31, 2012 Hazardous Air Pollutant Emissions MW	Mar. 31, 2012 Hazardous Air Pollutant Emissions FES	Mar. 08, 2012 Hazardous Air Pollutant Emissions FGCO MW	Mar. 31, 2012 Climate Change celsius	Jan. 02, 2011 Climate Change T	Mar. 31, 2012 Parental Guarantees	Mar. 31, 2012 Subsidiaries' Guarantees	Mar. 31, 2012 Other Guarantees	Mar. 31, 2012 Year 2020 Climate Change Increase in funding
Guarantor Obligations [Line Items]
Outstanding guarantees and other assurances aggregated	$ 4,100,000,000																												$ 900,000,000	$ 2,500,000,000	$ 700,000,000
Surety bonds and related guarantees	151,000,000
Maximum exposure under collateral provisions	671,000,000		530,000,000				68,000,000
Company Posted Collateral Related To Net Liability Positions			84,000,000				1,000,000
Potential Collateral Posted Related to Net Liability Positions			54,000,000				18,000,000
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
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
Megwatt Capacity for Retired Coal-Fired Power Plants																								3,349
Average percentage of power generation of retired coal-fired power plants																								10.00%
Measurement period for power generation of retired coal-fired power plants																								3 years
Megawatt capacity for proposed combusion turbine																										800
Pre-tax severance expense related to closures																								7,000,000	4,000,000
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
Options proposed by EPA for additional regulation of coal combustion residuals															2
Total environmental liabilities															106,000,000	70,000,000
Environmental Liabilities Former Gas Facilities															63,000,000
Decommissioning Fund Investments		2,112,000,000	1,240,000,000	1,223,000,000	195,000,000	193,000,000			0	0							2,135,000,000
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
Commitment Period by Developed Countries to Provide Funds, Years	3 years
Potential MATS Extension Period																								1 year