2.2.0.7 false Proposed Merger With Allegheny Energy, Inc. (Details) (USD $) 00615 - Disclosure - Proposed Merger With Allegheny Energy, Inc. (Details) true false false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Tons Standard http://firstenergycorp.com/20100331 tons fe 0 Percent Standard http://www.xbrl.org/2003/instance pure xbrli 0 kV Standard http://firstenergycorp.com/20100331 kV fe 0 Customers Standard http://firstenergycorp.com/20100331 Customers fe 0 Days Standard http://firstenergycorp.com/20100331 Days fe 0 EPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 3 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 4 USD false false Percent Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 3 Proposed Merger With Allegheny Energy, Inc. (Textuals) [Abstract] 1 fe_ProposedMergerTextualsAbstract fe false na duration Proposed Merger. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:stringItemType string Proposed Merger. false 4 Pursuant to the Merger Agreement, Right to receive portion of a share of common stock of FirstEnergy 2 fe_RightToReceivePortionOfShareOfCommonStockOfParentCompany fe false na instant Right to receive portion of a share of common stock of parent company. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false true false false 0.667 0.667 false false false xbrli:decimalItemType decimal Right to receive portion of a share of common stock of parent company. No authoritative reference available. false 5 Portion held by stockholders of Allegheny Energy in combined entity 2 fe_PortionHeldByStockholdersOfSubsidiaryCompanyInCombinedEntity fe false na instant Portion held by stockholders of subsidiary company in combined entity false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false true false false 27 27 false false false us-types:percentItemType pure Portion held by stockholders of subsidiary company in combined entity No authoritative reference available. false 6 Merger transactions costs 2 us-gaap_PaymentsForMergerRelatedCosts us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 true true false false 7000000 7000000 false false false 2 true true false false 21000000 21000000 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary The amount of cash paid during the reporting period for charges associated with the mergers. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 7 Merger transactions costs, net of tax 2 fe_MergerTransactionsCostsNetOfTax fe false credit duration Merger transactions costs, Net of tax. false false false false false false false false false false false verboselabel false 1 false true false false 5000000 5000000 false false false 2 false true false false 15000000 15000000 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary Merger transactions costs, Net of tax. No authoritative reference available. false 8 Shareholder value at merger agreement date 2 fe_ShareholderValueAtMergerAgreementDate fe false credit instant Shareholder value at merger agreement date. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false 4 false true false false 27.65 27.65 false false false xbrli:monetaryItemType monetary Shareholder value at merger agreement date. No authoritative reference available. false 9 Shareholder value at effectiveness date 2 fe_ShareholderValueAtEffectivenessDate fe false credit instant Shareholder value at effectiveness date. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 25.06 25.06 false false false 4 false false false false 0 0 false false false xbrli:monetaryItemType monetary Shareholder value at effectiveness date. No authoritative reference available. false 4 7 false NoRounding UnKnown UnKnown true true