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3/31/2011 USD ($) $ThreeMonthsEnded_31Mar2011_Fremont_Energy_Center_Memberhttp://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseFremont Energy Centerfe_BusinessUnitsAxisxbrldihttp://xbrl.org/2006/xbrldife_FremontEnergyCenterMemberfe_BusinessUnitsAxisexplicitMemberMWHStandardhttp://firstenergycorp.com/2011-03-31MWHfe0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4falsefalsetruefalse{fe_BusinessUnitsAxis} : Fremont Energy Center [Member] 3/11/2011 BalanceAsOf_11Mar2011_Fremont_Energy_Center_Memberhttp://www.sec.gov/CIK0001031296instant2011-03-11T00:00:000001-01-01T00:00:00falsefalseFremont Energy Centerfe_BusinessUnitsAxisxbrldihttp://xbrl.org/2006/xbrldife_FremontEnergyCenterMemberfe_BusinessUnitsAxisexplicitMemberPureStandardhttp://www.xbrl.org/2003/instancepurexbrli05falsefalseUSDtruefalse{fe_BusinessUnitsAxis} : Peaking Facilities [Member] 1/1/2011 - 3/31/2011 USD ($) $ThreeMonthsEnded_31Mar2011_Peaking_Facilities_Memberhttp://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00falsefalsePeaking Facilitiesfe_BusinessUnitsAxisxbrldihttp://xbrl.org/2006/xbrldife_PeakingFacilitiesMemberfe_BusinessUnitsAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2true0fe_ImpairmentOfLongLivedAssetsTextualsAbstractfefalsenadurationImpairment of long-lived assets.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringImpairment of long-lived assets.falsefalseImpairment of Long-Lived Assets (Textuals) [Abstract]3false0fe_NumberOfGasCombinedCycleCombustionTurbinesSoldfefalsenainstantNumber of gas combined cycle combustion turbines sold.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4truefalsefalse22falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:integerItemTypeintegerNumber of gas combined cycle combustion turbines sold.No authoritative reference available.falsefalseNumber of gas combined cycle combustion turbines sold4false0fe_LoadFollowingCapacityfefalsenadurationLoad following capacity.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse544544falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:integerItemTypeintegerLoad following capacity.No authoritative reference available.falsefalseLoad following capacity5false0fe_PeakingCapacityfefalsenadurationPeaking capacity.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse163163falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:integerItemTypeintegerPeaking capacity.No authoritative reference available.falsefalsePeaking capacity6false0us-gaap_AssetImpairmentChargesus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse3100000031falsetruefalsefalsefalse2truefalsefalse1200000012falsetruefalsefalsefalse3truefalsefalse1100000011falsetruefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5truefalsefalse1400000014falsetruefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 45, 46, 47 falsefalseAsset impairments7false0fe_NumberOfEventsOccuredfefalsenadurationNumber of events occured.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse22falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:integerItemTypeintegerNumber of events occured.No authoritative reference available.falsefalseNumber of events occured56Impairment of Long-Lived Assets (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruetrue