XML 55 R43.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Fair Value Measurements (Details 1) - Level 3 - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2017 | Dec. 31, 2016
NUG contracts |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | $ 1 | $ 1
Beginning Balance, Derivative Liabilities | (108) | (137)
Beginning Balance, Net | (107) | (136)
Unrealized gain (loss), Derivative Assets | 0 | 2
Unrealized gain (loss), Derivative Liabilities | (6) | (17)
Unrealized gain (loss), Net | (6) | (15)
Purchases, Derivative Assets |  | 0
Purchases, Derivative Liabilities |  | 0
Purchases, Net |  | 0
Settlements, Derivative Assets | (1) | (2)
Settlements, Derivative Liabilities | 11 | 46
Settlements, Net | 10 | 44
Ending Balance, Derivative Assets | 0 | 1
Ending Balance, Derivative Liabilities | (103) | (108)
Ending Balance, Net | (103) | (107)
FTRs |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | 7 | 8
Beginning Balance, Derivative Liabilities | (6) | (13)
Beginning Balance, Net | 1 | (5)
Unrealized gain (loss), Derivative Assets | 0 | (6)
Unrealized gain (loss), Derivative Liabilities | (1) | (4)
Unrealized gain (loss), Net | (1) | (10)
Purchases, Derivative Assets |  | 16
Purchases, Derivative Liabilities |  | (7)
Purchases, Net |  | 9
Settlements, Derivative Assets | (7) | (11)
Settlements, Derivative Liabilities | 3 | 18
Settlements, Net | (4) | 7
Ending Balance, Derivative Assets | 0 | 7
Ending Balance, Derivative Liabilities | (4) | (6)
Ending Balance, Net | (4) | 1
FTRs | FES |  |
Reconciliation of changes in the fair value of FTRs contracts |  |
Beginning Balance, Derivative Assets | 4 | 5
Beginning Balance, Derivative Liabilities | (5) | (11)
Beginning Balance, Net | (1) | (6)
Unrealized gain (loss), Derivative Assets |  | (4)
Unrealized gain (loss), Derivative Liabilities |  | (3)
Unrealized gain (loss), Net |  | (7)
Purchases, Derivative Assets |  | 10
Purchases, Derivative Liabilities |  | (5)
Purchases, Net |  | 5
Settlements, Derivative Assets | (4) | (7)
Settlements, Derivative Liabilities | 3 | 14
Settlements, Net | (1) | 7
Ending Balance, Derivative Assets | 0 | 4
Ending Balance, Derivative Liabilities | (2) | (5)
Ending Balance, Net | $ (2) | $ (1)

X
- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset and liability purchases total. + References No definition available. + Details
Name: | fe_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilityPurchases
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value measurement with unobservable inputs reconciliation recurring basis asset and liability settlements total. + References No definition available. + Details
Name: | fe_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilitySettlements
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset unrealized gain loss + References No definition available. + Details
Name: | fe_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetunrealizedgainloss
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Liability unrealized gain loss. + References No definition available. + Details
Name: | fe_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityUnrealizedGainLoss
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value measurement with unobservable inputs reconciliation recurring basis unrealized gain (loss) total. + References No definition available. + Details
Name: | fe_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisUnrealizedGainLoss
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value measurements with unobservable inputs reconciliation recurring basis asset and liability net value. + References No definition available. + Details
Name: | fe_FairValueMeasurementsWithUnobservableInputsReconciliationRecurringBasisAssetAndLiabilityNetValue
Namespace Prefix: | fe_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPurchases
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilitySettlements
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
Name: | us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationsRecurringBasisLiabilityValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=fe_NonUtilityGenerationContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=fe_FtrsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=fe_FesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |