Commitments, Guarantees and Contingencies (Details Textuals) (USD $)	3 Months Ended	12 Months Ended					12 Months Ended		12 Months Ended		12 Months Ended			12 Months Ended													12 Months Ended			12 Months Ended					12 Months Ended									12 Months Ended				12 Months Ended					12 Months Ended						1 Months Ended
	Jun. 30, 2011	Dec. 31, 2011 Complaints options IndividualsInAComplaint NuclearPowerPlants MW	Dec. 31, 2010 auctions	Dec. 31, 2009	Dec. 31, 2011 FGCO	Dec. 31, 2010 FGCO	Dec. 31, 2011 JCP&L lawsuits plantiffs	Dec. 31, 2010 JCP&L	Dec. 31, 2011 OE	Dec. 31, 2010 OE	Dec. 31, 2011 NGC	Dec. 31, 2011 TE	Dec. 31, 2010 TE	Dec. 31, 2011 Met-Ed, Penelec and JCP&L	Dec. 31, 2011 FES	Dec. 31, 2010 FES	Dec. 31, 2009 FES	Dec. 31, 2011 AE Supply	Dec. 31, 2011 Signal Peak and Global Rail	May 02, 2011 AE Supply and MP	Dec. 31, 2011 Material Adverse Event		Dec. 31, 2011 Material Adverse Event FES		Dec. 31, 2011 Material Adverse Event AE Supply		Dec. 31, 2011 Class Action ElectricGenerationUnits	Dec. 31, 2011 Climate change celsius	Jan. 02, 2011 Climate change T	Dec. 31, 2011 Climate change Increase in funding	Dec. 31, 2011 National Ambient Air Quality Standards T	Dec. 31, 2011 State Air Quality Compliance	Dec. 31, 2011 Caa Compliance Complaints CoalFiredPlants	Dec. 31, 2011 Caa Compliance 2015	Dec. 31, 2011 Caa Compliance FGCO plantiffs	Mar. 28, 2011 Nuclear Plant Matters Shortfall	Jun. 24, 2011 Nuclear Plant Matters Proposed Guarantee	Dec. 31, 2011 Regulation of Waste Disposal	Dec. 31, 2011 Regulation of Waste Disposal FE	Dec. 31, 2011 Regulation of Waste Disposal CEI	Dec. 31, 2011 Regulation of Waste Disposal FGCO	Dec. 31, 2011 Regulation of Waste Disposal JCP&L	Dec. 31, 2011 Regulation of Waste Disposal TE	Dec. 31, 2011 Monongahela River Water Quality	Dec. 31, 2010 Monongahela River Water Quality Miles	Dec. 31, 2011 Clean Water Act	Jun. 30, 2011 Clean Water Act	Dec. 31, 2011 CAIR [Member] phases	Dec. 31, 2011 CSAPR [Member] phases	Dec. 31, 2011 Parent Company	Dec. 31, 2011 Subsidiaries	Dec. 31, 2011 Surety Bonds And Lines Of Credit [Member]	Dec. 31, 2011 Competitive Energy Services [Member] Mono-Nitrogen Oxide Emission Allowances [Member]	Dec. 31, 2011 Competitive Energy Services [Member] Mono-Nitrogen Oxide Emission Allowances [Member] FES	Dec. 31, 2011 Competitive Energy Services [Member] Mono-Nitrogen Oxide Emission Allowances [Member] AE Supply	Dec. 31, 2011 Competitive Energy Services [Member] Sulfur Dioxide Emission Allowances [Member]	Dec. 31, 2011 Competitive Energy Services [Member] Sulfur Dioxide Emission Allowances [Member] FES	Dec. 31, 2011 Competitive Energy Services [Member] Sulfur Dioxide Emission Allowances [Member] AE Supply	Jan. 31, 2012 Settlement of Litigation [Member] Nuclear Plant Matters
Commitments Guarantees and Contingencies [Line Items]
Public Utilities, Liability Asses with Respect to Single Nuclear Incident Based On Act		$ 12,600,000,000
Expected Number of Nuclear Power Plant Licensed to Operate		104
Portion of Insurance Coverage of Private Insurer included in Single Nuclear Incident Liability		375,000,000
Portion of Insurance Coverage by Industry Retrospective Rating Plan		12,200,000,000
Company Posted Collateral Related To Net Liability Positions															88,000,000			1,000,000
Potential Collateral Posted Related to Net Liability Positions															49,000,000			24,000,000
Losses in Excess of Private Insurance Contributed for Each Nuclear Unit License		118,000,000
Losses in Excess of Private Insurance Contributed for Each Nuclear Unit License Per Unit		18,000,000
Nuclear Incidence Liability Per Incident of Parent and Subsidiary Companys Based On Their Present Nuclear Ownership and Leasehold Interests		470,000,000							40,000,000		408,000,000	22,000,000
Nuclear Incident Liability Not More Than In Any One Year Per Incident of Parent and Subsidiary Companies Based On Their Present Nuclear Ownership and Leasehold Interests		70,000,000							6,000,000		61,000,000	3,000,000
Nuclear Insurance Policy, Aggregate Indemnity		2,000,000,000							168,000,000		1,700,000,000	90,000,000
Nuclear Insurance Policy, Maximum Aggregate Assessments for Incidents at any Covered Nuclear Facility		13,000,000							1,000,000		12,000,000	1,000,000
Coverage of Decontamination Costs As Per Property Damage Insurance		2,800,000,000
Retrospective Assessments Liabilities		66,000,000							6,000,000		57,000,000	2,000,000		1,000,000
Insurance Coverage For Replacement Power Costs		1,100,000,000
Time Period After Stabilization That Licensees Are Required to Submit Cleanup Plans		30 days
Outstanding guarantees and other assurances aggregated		3,700,000,000																																																900,000,000	2,500,000,000	300,000,000
Surety bonds and related guarantees		151,000,000
Schedule of Insured Financial Obligations with Credit Deterioration, Insured Contractual Payments Outstanding		636,000,000
Senior Secured Term Loan Facility, Term, Years		2 years
Reduction in air emissions and compliance																																		81.00%
Required reduction in mercury by the beginning of 2010																																80.00%
Number of RGGI auctions held			14
Number of phases under the EPA’s CAIR for reductions of Sulfur Dioxide and Mono-Nitrogen Oxides																																																2	2
Days In Federal Register		60 days
Capping of SO2 Emissions Under CSAPR																															2,400,000
Outstanding collateral payments															52,000,000			1,000,000
Outstanding collateral payments additional requirement															28,000,000			2,000,000
Signal Peak and Global Rail entered into a syndicated two-year senior secured term loan facility																			350,000,000
Maximum exposure under collateral provisions		636,000,000													499,000,000			68,000,000			103,000,000	[1]	31,000,000	[1]	60,000,000	[1]
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							9																												8
Number of days required prior to the filing of a citizen suit under notice																																															60 days
Capping of SO2 emissions (In Tons)																															2,500,000
Capping of NOx emissions under CSAPR																															1,200,000
Asset impairments		413,000,000	388,000,000	6,000,000											294,000,000	388,000,000	6,000,000																																				6,000,000	1,000,000	5,000,000	21,000,000	18,000,000	3,000,000
Megwatt Capacity for Retired Coal-Fired Power Plants		3,349
Retired Coal-Fired Power Plants, Total		9
Electricity Produced by Retired Coal-Fired Power Plants, Percent		10.00%
Time Period for Retired Coal-Fired Power Plants		3 years
Capping of NOx emissions (In Tons)																															1,300,000
Non-Attainment Ozone Time Period, Hours		P8H
Upper threshold limit for carbon di oxide emission (Tons per Year)																													75,000
Increase (Decrease) in Global Temperature																												2
Total environmental liabilities																																						106,000,000	33,000,000	1,000,000	1,000,000	70,000,000	1,000,000
Parental guarantee associated with the funding of decommissioning costs																																				92,500,000	95,000,000
Settlement of claims																																																											48,000,000
Elevation of Sub-Surface Hairline Cracks, Feet		780
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
Environmental Liabilities Former Gas Facilities																																						63,000,000
Number of electric generation facilities																																	10
Number of generation units																											22
Sulfate Impairment Designation For Approximately Mile Stretch Of River		5 years
Options proposed by EPA for additional regulation of coal combustion residuals		2
Estimated clean up cost		59,000,000
Additional expenses recognized for clean up cost	29,000,000
Previously reserved clean up cost			30,000,000
Class action lawsuits no longer certified as class action							2
Decommissioning Fund Investments		2,112,000,000	1,973,000,000		0	0	193,000,000	182,000,000	137,000,000	127,000,000		83,125,000	75,558,000		1,223,000,000	1,146,000,000
Loss incurred in damages for replacement coal purchased																		80,000,000
Annual percentage that fish impingement should be reduced to, per CWA																																														12.00%
Extension of comment period		30 days
Request For Information from Number of Nuclear Power Plants, Total		11
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
Sulfate Impairment Designation For Approximately Mile Stretch Of River, Miles																																													68
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

[1] Includes $31 million that is also considered an acceleration of payment or funding obligation at FES.