Deferred Tax Assets, Increase in Operating Loss Carryforwards During Period

No definition available.

Name:	fe_DeferredTaxAssetsIncreaseInOperatingLossCarryforwardsDuringPeriod
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Disposal Group, Including Discontinued Operation, Worthless Stock Deduction

+ References

No definition available.

+ Details

Name:	fe_DisposalGroupIncludingDiscontinuedOperationWorthlessStockDeduction
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Disposal Group, Including Discontinued Operation, Worthless Stock Deduction, Net of Tax

+ References

No definition available.

+ Details

Name:	fe_DisposalGroupIncludingDiscontinuedOperationWorthlessStockDeductionNetofTax
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Operating Loss Carryforwards, Increase During Period

+ References

No definition available.

+ Details

Name:	fe_OperatingLossCarryforwardsIncreaseDuringPeriod
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Unrecognized Tax Benefits, Increase Resulting from Change in Worthless Stock Deduction Reserve, Gross

+ References

No definition available.

+ Details

Name:	fe_UnrecognizedTaxBenefitsIncreaseResultingfromChangeinWorthlessStockDeductionReserveGross
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Unrecognized Tax Benefits, Increase Resulting from Change in Worthless Stock Deduction Reserve, Net of Tax

+ References

No definition available.

+ Details

Name:	fe_UnrecognizedTaxBenefitsIncreaseResultingfromChangeinWorthlessStockDeductionReserveNetofTax
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount paid to settle bankruptcy claim.

+ References

No definition available.

+ Details

Name:	us-gaap_BankruptcyClaimsAmountPaidToSettleClaims
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of cash inflow (outflow) of financing activities of discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

+ References

+ Details

Name:	us-gaap_CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow (outflow) of investing activities of discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 24
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3521-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760

+ Details

Name:	us-gaap_CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash inflow (outflow) of operating activities of discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

+ References

+ Details

Name:	us-gaap_CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DiscontinuedOperationsDisposedOfByMeansOtherThanSaleMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=fe_FESandFENOCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=fe_FESKeyCreditorGroupsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fe_FesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=fe_ITAccessAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Discontinued Operations - Narrative (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Feb. 27, 2020	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash provided by investing activities from discontinued operations			$ 0	$ 0
Cash provided by financing activities from discontinued operations			0	0
Worthless stock deduction	$ 4,900
Unrecognized tax benefits from worthless stock deduction	316
Worthless stock deduction, net of tax	1,000
Unrecognized tax benefits from worthless stock deduction, net of tax	68
Increase in NOL allocation		$ 289
Increase in NOL allocation tax effected		$ 61
Discontinued Operations, Disposed of by Means Other than Sale \| FES and FENOC
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash flows from operating activities, discontinued operations			$ 47	$ 46
FES Key Creditor Groups \| Affiliated Companies \| FES
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of claims upon emergence	853
IT Access Agreement \| Affiliated Companies \| FES
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Settlement of claims upon emergence	125
State and Local Jurisdiction
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Worthless stock deduction, net of tax	$ 19