XML 55 R37.htm IDEA: XBRL DOCUMENT
v3.23.3

PENSION AND OTHER POST-EMPLOYMENT BENEFITS - Narrative (Details) $ in Millions |  |  |  | 3 Months Ended | 8 Months Ended | 9 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
May 12, 2023 USD ($) | Apr. 30, 2023 | Dec. 31, 2022 | Jun. 30, 2023 USD ($) | Dec. 31, 2023 | Sep. 30, 2023 USD ($) | Sep. 30, 2022 USD ($) | May 09, 2023 employee
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |
Percent of eligible employees that accepted the voluntary retirement program |  |  |  |  |  |  |  | 0.65
Number of employees | employee |  |  |  |  |  |  |  | 450
Number of separated employees | employee |  |  |  |  |  |  |  | 90
Defined benefit plan, assumptions used calculating benefit obligation, increase (decrease) in discount rate |  |  |  | 0.29% |  |  |  |
Pension |  |  |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |
Voluntary cash contribution | $ 750 |  |  |  |  |  |  |
Voluntary contribution, percentage |  | 7.70% |  |  |  |  |  |
Estimated return |  |  |  |  |  | 800.00% |  |
Discount rate |  | 4.94% | 5.23% |  |  |  |  |
Pension and OPEB mark-to-market adjustment |  |  |  |  |  | $ (59) | $ 0 |
Pension | Forecast |  |  |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |
Estimated return |  |  |  |  | 5.30% |  |  |
Discount rate |  |  |  |  | 8.00% |  |  |
OPEB |  |  |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |
Estimated return |  |  |  |  |  | 7.00% |  |
Discount rate |  |  | 5.16% |  |  |  |  |
Pension and OPEB mark-to-market adjustment |  |  |  |  |  | $ 0 | $ 0 |
Pension Mark-to-market Adjustment |  |  |  |  |  |  |  |
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] |  |  |  |  |  |  |  |
Net periodic benefit cost, pre-tax |  |  |  | $ 47 |  |  |  |

X
- Definition Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Increase (Decrease) in Discount Rate + References No definition available. + Details
Name: | fe_DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationIncreaseDecreaseInDiscountRate
Namespace Prefix: | fe_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Pre- Tax + References No definition available. + Details
Name: | fe_DefinedBenefitPlanNetPeriodicBenefitCostCreditPreTax
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Defined Benefit Plan, Number of Employees + References No definition available. + Details
Name: | fe_DefinedBenefitPlanNumberOfEmployees
Namespace Prefix: | fe_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan, Number Of Separated Employees + References No definition available. + Details
Name: | fe_DefinedBenefitPlanNumberOfSeparatedEmployees
Namespace Prefix: | fe_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan, Percentage of Employees Covered By Plan + References No definition available. + Details
Name: | fe_DefinedBenefitPlanPercentageOfEmployeesCoveredByPlan
Namespace Prefix: | fe_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Defined Benefit Plan, Voluntary Cash Contribution + References No definition available. + Details
Name: | fe_DefinedBenefitPlanVoluntaryCashContribution
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase (Decrease) to Net Periodic Benefit Cost Based on Mark-to-Market Adjustment + References No definition available. + Details
Name: | fe_IncreaseDecreaseToNetPeriodicBenefitCostBasedOnMarkToMarketAdjustment
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-8 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 715 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (k)(3) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480506/715-20-50-1 + Details
Name: | us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanDisclosureLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of plan assets to benefit obligation of defined benefit plan. + References No definition available. + Details
Name: | us-gaap_DefinedBenefitPlanFundedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RetirementPlanTypeAxis=fe_PensionMarkToMarketAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |