2.2.0.25truefalse06062 - Disclosure - Pension and Other Postretirement Benefit Plans (Details Textuals)truefalseIn Millions, unless otherwise specifiedfalse1falsefalseUSDfalsefalse1/1/2011 - 3/31/2011 USD ($) USD ($) / shares $Jan-01-2011_Mar-31-2011http://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0PureStandardhttp://www.xbrl.org/2003/instancepurexbrli0MWHStandardhttp://firstenergycorp.com/2011-03-31MWHfe0USDUSD$2falsefalseUSDfalsefalse1/1/2010 - 3/31/2010 USD ($) USD ($) / shares $ThreeMonthsEnded_31Mar2010http://www.sec.gov/CIK0001031296duration2010-01-01T00:00:002010-03-31T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDEPSDividehttp://www.xbrl.org/2003/iso4217USDiso4217http://www.xbrl.org/2003/instancesharesxbrli0SharesStandardhttp://www.xbrl.org/2003/instancesharesxbrli0USDUSD$3falsefalseUSDtruefalse{dei_LegalEntityAxis} : Allegheny Member {us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Pension Plans Defined Benefit [Member] 1/1/2011 - 3/31/2011 ThreeMonthsEnded_31Mar2011_Pension_Plans_Defined_Benefit_Member_Allegheny_Memberhttp://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseAlleghenydei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldife_AlleghenyMemberdei_LegalEntityAxisexplicitMemberfalsefalsePension Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PensionPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberPureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$4falsefalseUSDtruefalse{dei_LegalEntityAxis} : Allegheny Member {us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Pension Plans Defined Benefit [Member] 2/25/2011 USD ($) $BalanceAsOf_25Feb2011_Allegheny_Member_Pension_Plans_Defined_Benefit_Memberhttp://www.sec.gov/CIK0001031296instant2011-02-25T00:00:000001-01-01T00:00:00falsefalseAlleghenydei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldife_AlleghenyMemberdei_LegalEntityAxisexplicitMemberfalsefalsePension Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PensionPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5falsefalseUSDtruefalse{us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Pension Plans Defined Benefit [Member] 1/1/2011 - 3/31/2011 USD ($) $ThreeMonthsEnded_31Mar2011_Pension_Plans_Defined_Benefit_Memberhttp://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00falsefalsePension Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PensionPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$6falsefalseUSDtruefalse{dei_LegalEntityAxis} : Allegheny Member {us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Other Postretirement Benefit Plans Defined Benefit [Member] 1/1/2011 - 3/31/2011 ThreeMonthsEnded_31Mar2011_Other_Postretirement_Benefit_Plans_Defined_Benefit_Member_Allegheny_Memberhttp://www.sec.gov/CIK0001031296duration2011-01-01T00:00:002011-03-31T00:00:00falsefalseAlleghenydei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldife_AlleghenyMemberdei_LegalEntityAxisexplicitMemberfalsefalseOther Postretirement Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberPureStandardhttp://www.xbrl.org/2003/instancepurexbrli0USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$7falsefalseUSDtruefalse{dei_LegalEntityAxis} : Allegheny Member {us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Other Postretirement Benefit Plans Defined Benefit [Member] 2/25/2011 USD ($) $BalanceAsOf_25Feb2011_Allegheny_Member_Other_Postretirement_Benefit_Plans_Defined_Benefit_Memberhttp://www.sec.gov/CIK0001031296instant2011-02-25T00:00:000001-01-01T00:00:00falsefalseAlleghenydei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldife_AlleghenyMemberdei_LegalEntityAxisexplicitMemberfalsefalseOther Postretirement Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$8falsefalseUSDtruefalse{us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis} : Other Postretirement Benefit Plans Defined Benefit [Member] 3/31/2011 USD ($) $BalanceAsOf_31Mar2011_Other_Postretirement_Benefit_Plans_Defined_Benefit_Memberhttp://www.sec.gov/CIK0001031296instant2011-03-31T00:00:000001-01-01T00:00:00falsefalseOther Postretirement Benefit Cost (Credit)us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherPostretirementBenefitPlansDefinedBenefitMemberus-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2true0fe_PensionAndOtherPostretirementBenefitPlansTextualsAbstractfefalsenadurationPension and other postretirement benefit plans.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseOtherxbrli:stringItemTypestringPension and other postretirement benefit plans.falsefalsePension And Other Postretirement Benefit Plans (Textuals) [Abstract]3false0us-gaap_PensionAndOtherPostretirementBenefitExpenseus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse2800000028falsetruefalsefalsefalse2truefalsefalse2400000024falsetruefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of pension and other (such as medical, dental and life insurance) postretirement benefit costs recognized during the period for (1) defined benefit plans (periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss on assets, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments) and for (2) defined contribution plans (to the extent that a plan's defined contributions to an individual's account are to be made for periods in which that individual renders services, the net cost for a period shall be the contribution called for in that period; if a plan calls for contributions for periods after an individual retires or terminates, the estimated cost shall be accrued during the employee's service period).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 132R -Paragraph 5 -Subparagraph h Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5, 11 falsefalseFirstEnergy's net pension and OPEB expense4false0us-gaap_DefinedBenefitPlanContributionsByEmployerus-gaaptruedebitdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5truefalsefalse157000000157falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe amount of contributions made by the employer.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b falsefalseEmployer Contribution for qualified Plans5false0us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYearus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5truefalsefalse220000000220falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8truefalsefalse60000006falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryThe employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph g falsefalseExpected Additional Employer Contribution In Next Fiscal Year6false0us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRateus-gaaptruenainstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsetruefalse00falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalse3truetruefalse0.05500.0550falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6truetruefalse0.05250.0525falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse8falsetruefalse00falsefalsefalsetruefalseOtherus-types:percentItemTypepureThe interest rate used to adjust for the time value of money for the plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph j falsefalseDiscount rate used to measure funded status7false0fe_DefinedBenefitPlanAccumulatedBenefitObligationReducedAmountfefalsecreditinstantDefined benefit plan accumulated benefit obligation reduced amount.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3truefalsefalse60000006falsefalsefalsetruefalse4falsefalsefalse00falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6truefalsefalse20000002falsefalsefalsetruefalse7falsefalsefalse00falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryDefined benefit plan accumulated benefit obligation reduced amount.No authoritative reference available.falsefalseAccumulated benefit obligation reductions as a result of fair value measurement8false0us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssetsus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsetruefalse00falsefalsefalsefalsefalse2falsetruefalse00falsefalsefalsefalsefalse3truetruefalse0.08250.0825falsefalsefalsetruefalse4falsetruefalse00falsefalsefalsetruefalse5falsetruefalse00falsefalsefalsetruefalse6truetruefalse0.05000.0500falsefalsefalsetruefalse7falsetruefalse00falsefalsefalsetruefalse8falsetruefalse00falsefalsefalsetruefalseOtherus-types:percentItemTypepureAn assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph j falsefalseExpected returns on plan assets used to calculate net period costs9false0us-gaap_DefinedBenefitPlanFairValueOfPlanAssetsus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4truefalsefalse954000000954falsefalsefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7truefalsefalse7500000075falsefalsefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetaryAssets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those nonbenefit obligations may be considered as reductions of plan assets.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph d(iv)(b)(i) Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 49 falsefalseFair value of plan assets10false0us-gaap_DefinedBenefitPlanBenefitObligationus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsetruefalse4truefalsefalse13410000001341falsetruefalsetruefalse5falsefalsefalse00falsefalsefalsetruefalse6falsefalsefalse00falsefalsefalsetruefalse7truefalsefalse272000000272falsetruefalsetruefalse8falsefalsefalse00falsefalsefalsetruefalseMonetaryxbrli:monetaryItemTypemonetary1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. The projected benefit obligation is measured using assumptions as to future compensation levels if the pension benefit formula is based on those future compensation levels (pay-related, final-pay, final-average-pay, or career-average-pay plans). For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. Prior to an employee's full eligibility date, the accumulated postretirement benefit obligation as of a particular date for an employee is the portion of the expected postretirement benefit obligation attributed to that employee's service rendered to that date; on and after the full eligibility date, the accumulated and expected postretirement benefit obligations for an employee are the same.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 -Subparagraph a Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph E1 falsefalseActuarially determined benefit obligations89Pension and Other Postretirement Benefit Plans (Details Textuals) (USD $)MillionsUnKnownUnKnownUnKnowntruetrue