Commitments, Guarantees and Contingencies (Details Textuals) (USD $)	9 Months Ended		21 Months Ended					9 Months Ended	12 Months Ended		9 Months Ended			9 Months Ended				3 Months Ended	9 Months Ended			9 Months Ended			9 Months Ended			9 Months Ended		9 Months Ended	3 Months Ended			3 Months Ended	9 Months Ended			9 Months Ended			16 Months Ended	9 Months Ended							0 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 05, 2011 allegation aspect_of_opinion	Dec. 31, 2011	Nov. 07, 2012 Natural Disasters and Other Casualty Events	Oct. 31, 2012 Natural Disasters and Other Casualty Events Customers professional	Nov. 07, 2012 Natural Disasters and Other Casualty Events New Jersey Customers	Sep. 30, 2012 Clean Water Act	Dec. 31, 2010 Clean Water Act mi	Apr. 30, 2009 Clean Water Act aspect_of_opinion	Sep. 30, 2012 Regulation of Waste Disposal options	Sep. 30, 2012 Nuclear Plant Matters canister	Feb. 16, 2012 Nuclear Plant Matters NuclearPowerPlants	Sep. 30, 2012 Caa Compliance ElectricGenerationUnits CoalFiredPlants	Sep. 30, 2012 National Ambient Air Quality Standards T	Sep. 30, 2012 National Ambient Air Quality Standards CAIR phases	Sep. 30, 2012 National Ambient Air Quality Standards CSAPR phases	Sep. 30, 2012 Hazardous Air Pollutant Emissions CoalFiredPlants MW	Sep. 30, 2012 Hazardous Air Pollutant Emissions CoalFiredPlants MW	Sep. 30, 2012 Climate Change celsius	Jan. 02, 2011 Climate Change T	Sep. 30, 2012 Climate Change Year 2020 Increase in funding	Sep. 30, 2012 Senior Secured Term Loan Senior Loans	Sep. 30, 2012 Regulated Distribution	Sep. 30, 2012 FES	Sep. 30, 2011 FES	Dec. 31, 2011 FES	Sep. 30, 2012 FES Hazardous Air Pollutant Emissions	Sep. 30, 2012 AE Supply	Sep. 30, 2012 AE Supply ICG Litigation	Sep. 30, 2012 Global Holding	Sep. 30, 2012 Global Holding Senior Secured Term Loan Senior Loans	Sep. 30, 2012 Global Holding Senior Secured Term Loan Senior Loans Signal Peak, Global Rail and Affiliates	Sep. 30, 2012 Signal Peak and Global Rail	Sep. 30, 2012 Signal Peak and Global Rail Senior Secured Term Loan Senior Loans	Sep. 30, 2012 FEV Senior Secured Term Loan Senior Loans Signal Peak Global Holding	Sep. 30, 2012 WMB Marketing Ventures, LLC Senior Secured Term Loan Senior Loans Signal Peak Global Holding	Sep. 30, 2012 FGCO	Sep. 30, 2011 FGCO	Dec. 31, 2011 FGCO	Feb. 27, 2007 FGCO Clean Water Act spills	Sep. 30, 2012 FGCO Caa Compliance Complaints	Sep. 30, 2012 FGCO Caa Compliance Claim One Complaints IndividualsInAComplaint	Sep. 30, 2012 FGCO Caa Compliance Claim Two plantiffs	Sep. 30, 2012 JCP&L	Sep. 30, 2011 JCP&L	Dec. 31, 2011 JCP&L	Sep. 30, 2012 JCP&L Regulation of Waste Disposal	Aug. 13, 2012 AE Supply and MP ICG Litigation	May 02, 2011 AE Supply and MP ICG Litigation	Sep. 30, 2012 Parental Guarantees	Sep. 30, 2012 Subsidiaries' Guarantees	Sep. 30, 2012 Other Guarantees
Guarantor Obligations [Line Items]
Outstanding guarantees and other assurances aggregated	$ 4,100,000,000																																																		$ 900,000,000	$ 2,400,000,000	$ 700,000,000
Company posted collateral related to net liability positions																								21,000,000	73,000,000
Potential collateral posted related to net liability positions																									40,000,000				11,000,000
Senior secured term loan facility, term																															3 years			2 years
New syndicated senior secured term loan facility																																350,000,000
Repayments of senior secured term loan facility	870,000,000	1,581,000,000																							246,000,000	791,000,000									350,000,000			169,000,000	351,000,000						24,000,000	23,000,000
Investment ownership percentage																																	69.99%			33.33%	33.33%
Guarantor obligations, guarantee fee receivable, percentage, remainder of fiscal year																							4.00%
Guarantor obligations, guarantee fee receivable, percentage, next twelve months																							5.00%
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
Potential cost of compliance, MATS																		975,000,000	975,000,000
Number of retired coal-fired plants being retired																		9	9
Megawatt capacity of plants expected to be closed																		3,349	3,349
Pre-tax severance expense related to closures																			14,000,000									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
Commitment Period by Developed Countries to Provide Funds, Years																				3 years
Aspects of opinion reversed										1
Annual percentage that fish impingement should be reduced to, per CWA								12.00%
Petroleum spills																																									3
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											123,000,000																																					86,000,000
Environmental Liabilities Former Gas Facilities											79,000,000
Decommissioning Fund Investments	2,203,000,000			2,112,000,000								2,000,000,000													1,286,000,000		1,223,000,000											0		0					199,000,000		193,000,000
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
Final rule, determination period												24 months
Number of cooling canisters to be installed												6
Number of cooling canisters, additional installation capacity												47
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
Gain contingency, unrecorded amount																																																	14,000,000
Potential MATS Extension Period																		1 year
Number of allegations remanded to trial court			1
Aspects of opinion under appeal			1
Gain contingency, damages denied																																																	90,000,000
Gain contingency, appeal period																																																	30 days
Number of customers impacted by power outage						2,300,000	1,200,000
Number of professionals working to resolve power outage						20,000
Percentage of impacted customers with power restored					95.00%		85.00%
Expected costs due to catastrophic event					$ 500,000,000
Percentage of expected cost expected to be capitalized or deferred					95.00%