Bond Closure and Post Closure Period

No definition available.

Name:	fe_BondClosureandPostClosurePeriod
Namespace Prefix:	fe_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Capital Investment Required To Install Technology To Meet Tds And Sulfate Limits

+ References

No definition available.

+ Details

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

- Definition

Commitment, Proposed Regulation, Waste Water Discharge Permit, Renewal Cycle

+ References

No definition available.

+ Details

Name:	fe_CommitmentProposedRegulationWasteWaterDischargePermitRenewalCycle
Namespace Prefix:	fe_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Environmental Liabilities Former Gas Facilities.

+ References

No definition available.

+ Details

Name:	fe_EnvironmentalLiabilitiesFormerGasFacilities
Namespace Prefix:	fe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Period of Time to Implement Plan

+ References

No definition available.

+ Details

Name:	fe_PeriodOfTimeToImplementPlan
Namespace Prefix:	fe_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 25
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6395460&loc=d3e13647-108346

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13207-110859

+ Details

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

- Definition

Amount of increase (decrease) in asset retirement obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

+ Details

Name:	us-gaap_AssetRetirementObligationPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

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

- Details

Name:	fe_LossContingenciesByClaimsAxis=fe_RegulationOfWasteDisposalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fe_LossContingenciesByClaimsAxis=fe_CleanWaterActMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilityAxis=fe_PleasantsPowerStationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=fe_McElroysRunImpoundmentSiteMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_SuretyBondMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilityAxis=fe_LittleBullRunMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilityAxis=fe_HatfieldFerryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Commitments, Guarantees and Contingencies - Clean Water Act and Regulation of Waste Disposal (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018
Loss Contingencies [Line Items]
Renewal cycle of waste water discharge permit		5 years
Regulation of Waste Disposal
Loss Contingencies [Line Items]
Bond closure and post closure period		45 years
Period of time to implement plan		12 years
Accrual for environmental loss contingencies		$ 121,000,000
Environmental liabilities former gas facilities		85,000,000
Minimum \| Clean Water Act
Loss Contingencies [Line Items]
Maximum capital investment required to install technology to meet TDS and Sulfate limits		150,000,000
Maximum \| Clean Water Act
Loss Contingencies [Line Items]
Maximum capital investment required to install technology to meet TDS and Sulfate limits		300,000,000
Pleasants Power Station \| McElroy's Run Impoundment Site
Loss Contingencies [Line Items]
Increase in asset retirement obligation	$ 43,000,000
Pleasants Power Station \| AE Supply \| McElroy's Run Impoundment Site \| Regulation of Waste Disposal
Loss Contingencies [Line Items]
Increase in asset retirement obligation	$ 43,000,000
Line of Credit \| Surety Bond \| Little Bull Run
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility		169,000,000
Line of Credit \| Surety Bond \| Hatfield Ferry
Loss Contingencies [Line Items]
Maximum amount borrowed under revolving credit facility		$ 31,000,000