XML 83 R70.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Derivatives - Additional Information (Detail) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 USD ($) Derivatives | Mar. 31, 2017 USD ($) | Dec. 31, 2017 USD ($)
Risk participation Agreements [Line Items] |  |  |
HedgedItemsOfCashFlowHedge | $ 115,000 |  |
Risk Participation Agreements Purchased [Domain] |  |  |
Risk participation Agreements [Line Items] |  |  |
Number of interest rate swaps | Derivatives | 37 |  |
Risk Participation Agreements Sold [Domain] |  |  |
Risk participation Agreements [Line Items] |  |  |
Number of interest rate swaps | Derivatives | 12 |  |
Forward Contracts [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | $ (62) | $ 112 |
Derivative Liability, Cost Basis, Gross Asset | 7,000 |  | $ 14,300
Derivative Liability, Fair Value, Gross Asset | 7,200 |  | 14,700
Derivative Liability, Notional Amount, Gross Asset | 18,300 |  | 13,800
Forward Contracts [Member] | Designated as Hedging Instrument [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative, Fair Value, Net | (81) |  | (19)
Derivative, Notional Amount | 22,000 |  | 17,000
Foreign Exchange [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | (3) | 2 |
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative, Fair Value, Net | 13 |  | 70
Derivative, Notional Amount | 7,858 |  | 10,077
Derivative Liability, Cost Basis, Gross Asset | 7,800 |  | 10,000
Derivative Liability, Fair Value, Gross Asset | 7,800 |  | 10,100
Interest Rate Swap [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative Instruments Designated As Hedging Instruments Interest Income | (81) | 249 |
Derivative, Net Hedge Ineffectiveness Gain (Loss) | 0 | $ 78 |
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] |  |  |
Risk participation Agreements [Line Items] |  |  |
Derivative, Fair Value, Net | 590 |  | (459)
Derivative, Notional Amount | $ 115,000 |  | $ 150,000

X
- Definition Derivative Instruments Designated As Hedging Instruments Interest Income + References No definition available. + Details
Name: | fcf_DerivativeInstrumentsDesignatedAsHedgingInstrumentsInterestIncome
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Derivative Liability, Cost Basis, Gross Asset + References No definition available. + Details
Name: | fcf_DerivativeLiabilityCostBasisGrossAsset
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Derivative Liability, Notional Amount, Gross Asset + References No definition available. + Details
Name: | fcf_DerivativeLiabilityNotionalAmountGrossAsset
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition HedgedItemsOfCashFlowHedge + References No definition available. + Details
Name: | fcf_HedgedItemsOfCashFlowHedge
Namespace Prefix: | fcf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition [Line Items] for Risk participation Agreements [Table] + References No definition available. + Details
Name: | fcf_RiskparticipationAgreementsLineItems
Namespace Prefix: | fcf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
Name: | invest_DerivativeNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value of the assets less the liabilities of a derivative or group of derivatives. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=77997519&loc=d3e13495-108611 + Details
Name: | us-gaap_DerivativeFairValueOfDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value of asset associated with financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226003-175313 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959 + Details
Name: | us-gaap_DerivativeLiabilityFairValueGrossAsset
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of gain (loss) from the ineffectiveness of the hedge. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 25 -Section 50 -Paragraph 1 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986 + Details
Name: | us-gaap_DerivativeNetHedgeIneffectivenessGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of credit risk derivative instruments held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959 + Details
Name: | us-gaap_NumberOfCreditRiskDerivativesHeld
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | fcf_RiskParticipationAgreementsAxis=fcf_RiskParticipationAgreementsPurchasedDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | fcf_RiskParticipationAgreementsAxis=fcf_RiskParticipationAgreementsSoldDomain
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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