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v2.4.1.9

Fair Values of Assets and Liabilities - Quantitative Inputs and Assumptions Used in Level 3 Fair Value Measurements (Detail) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other Assets | 11,186,000us-gaap_OtherAssetsFairValueDisclosure |  | $ 14,358,000us-gaap_OtherAssetsFairValueDisclosure
Estimated Fair Value of Available for Sale | 1,309,819,000us-gaap_AvailableForSaleSecurities |  | 1,318,365,000us-gaap_AvailableForSaleSecurities
Total Debt Securities | 1,308,399,000us-gaap_DebtInstrumentFairValue |  | 1,316,945,000us-gaap_DebtInstrumentFairValue
Fair Value | 1,368,052,000us-gaap_AssetsFairValueDisclosure |  | 1,368,167,000us-gaap_AssetsFairValueDisclosure
Probability of default [Member] | Minimum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 0.00%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_ProbabilityOfDefaultMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Probability of default [Member] | Maximum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 100.00%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_ProbabilityOfDefaultMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Probability of default [Member] | Weighted Average [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 17.16%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_ProbabilityOfDefaultMember / us-gaap_RangeAxis = us-gaap_WeightedAverageMember |  |
Prepayment rates [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Prepayment rates |  |
Prepayment rates [Member] | Minimum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 0.00%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_PrepaymentRatesMember / us-gaap_RangeAxis = us-gaap_MinimumMember |  |
Prepayment rates [Member] | Maximum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 73.88%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_PrepaymentRatesMember / us-gaap_RangeAxis = us-gaap_MaximumMember |  |
Prepayment rates [Member] | Weighted Average [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 6.13%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_PrepaymentRatesMember / us-gaap_RangeAxis = us-gaap_WeightedAverageMember |  |
Discount rates [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Discount rates |  |
Gas per MCF [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Gas per MCF |  |
Gas per MCF [Member] | Minimum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average | 3.00fcf_FairValueWeightedAverageInputsPrice / us-gaap_FairValueByMeasurementBasisAxis = fcf_GasPerMillionCubicFeetMember / us-gaap_RangeAxis = us-gaap_MinimumMember | [1] |
Gas per MCF [Member] | Maximum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average | 4.85fcf_FairValueWeightedAverageInputsPrice / us-gaap_FairValueByMeasurementBasisAxis = fcf_GasPerMillionCubicFeetMember / us-gaap_RangeAxis = us-gaap_MaximumMember | [1] |
Oil per BBL/d [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Oil per BBL/d |  |
Oil per BBL/d [Member] | Minimum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average | 53.91fcf_FairValueWeightedAverageInputsPrice / us-gaap_FairValueByMeasurementBasisAxis = fcf_OilPerBarrelsPerDayMember / us-gaap_RangeAxis = us-gaap_MinimumMember | [1] |
Oil per BBL/d [Member] | Maximum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average | 71.01fcf_FairValueWeightedAverageInputsPrice / us-gaap_FairValueByMeasurementBasisAxis = fcf_OilPerBarrelsPerDayMember / us-gaap_RangeAxis = us-gaap_MaximumMember | [1] |
NGL per gallon [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | NGL per gallon |  |
NGL per gallon [Member] | Weighted Average [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average | 0.83fcf_FairValueWeightedAverageInputsPrice / us-gaap_FairValueByMeasurementBasisAxis = fcf_NaturalGasLiquidPerGallonMember / us-gaap_RangeAxis = us-gaap_WeightedAverageMember |  |
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Probability of default [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Probability of default |  |
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discount rates [Member] | Minimum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 5.25%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_DiscountRatesMember / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = fcf_PooledTrustPreferredCollateralizedDebtObligationsMember / us-gaap_RangeAxis = us-gaap_MinimumMember | [2] |
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discount rates [Member] | Maximum [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 14.00%us-gaap_FairValueInputsDiscountRate / us-gaap_FairValueByMeasurementBasisAxis = fcf_DiscountRatesMember / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = fcf_PooledTrustPreferredCollateralizedDebtObligationsMember / us-gaap_RangeAxis = us-gaap_MaximumMember | [2] |
Pooled Trust Preferred Collateralized Debt Obligations [Member] | Discounted Cash Flow [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Valuation Technique | Discounted Cash Flow |  |
Other Investments [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs |  |  |
Other Investments [Member] | Par Value [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Valuation Technique | Par Value |  |
Impaired Loans [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Fair Value | 4,116,000us-gaap_AssetsFairValueDisclosure / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = fcf_ImpairedLoansMember | [3] |
Impaired Loans [Member] | Weighted Average [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Weighted average rate | 10.00%us-gaap_FairValueInputsDiscountRate / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = fcf_ImpairedLoansMember / us-gaap_RangeAxis = us-gaap_WeightedAverageMember |  |
Impaired Loans [Member] | Discount rates [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs | Discount rate |  |
Impaired Loans [Member] | Reserve study [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Valuation Technique | Gas Reserve study |  |
Other Real Estate Owned [Member] | Counterparty credit risk [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Unobservable Inputs |  |  |
Other Real Estate Owned [Member] | Internal Valuation [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Valuation Technique | Internal Valuation |  |
Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other Assets |  |  | 0us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Estimated Fair Value of Available for Sale | 30,419,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  | 24,943,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Total Debt Securities | 28,999,000us-gaap_DebtInstrumentFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  | 23,523,000us-gaap_DebtInstrumentFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Fair Value | 30,419,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |  | 24,943,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Fair Value, Inputs, Level 3 [Member] | Interest rate swap [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other Assets | 0us-gaap_OtherAssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = us-gaap_InterestRateSwapMember |  |
Equities [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Estimated Fair Value of Available for Sale | 1,420,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember |  | 1,420,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Equities [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Estimated Fair Value of Available for Sale |  |  | 1,420,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Equities [Member] | Fair Value, Inputs, Level 3 [Member] | Other Investments [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Estimated Fair Value of Available for Sale | 1,420,000us-gaap_AvailableForSaleSecurities / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_MortgageLoansOnRealEstateLoanTypeAxis = us-gaap_OtherInvestmentsMember |  |
Fair Value, Measurements, Nonrecurring [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other real estate owned | 7,981,000fcf_OtherRealEstateOwnedAssetsFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember |  | 12,924,000fcf_OtherRealEstateOwnedAssetsFairValue / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember
Fair Value | 53,771,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember |  | 63,483,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other real estate owned | 153,000fcf_OtherRealEstateOwnedAssetsFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember |  | 172,000fcf_OtherRealEstateOwnedAssetsFairValue / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember
Fair Value | 11,079,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember |  | $ 13,828,000us-gaap_AssetsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_FairValueByMeasurementFrequencyAxis = us-gaap_FairValueMeasurementsNonrecurringMember
[1] | unobservable inputs are defined as follows: MCF—million cubic feet; BBL/d—barrels per day; NGL—natural gas liquid.
[2] | incorporates spread over the risk free rate related primarily to credit quality and illiquidity of securities.
[3] | the remainder of impaired loans valued using Level 3 inputs are not included in this disclosure as the values of those loans are based on bankruptcy agreement documentation.

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- Definition Other real estate owned assets fair value. + References No definition available. + Details
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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + 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 (a) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562 + Details
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- Definition Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. + References Reference 1: 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=35750535&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13476-108611 + Details
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- Definition Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt. + 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 (bbb) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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