| **Impairment of Investment Securities - Schedule of Unrealized Losses and Estimated Fair Values (Detail) (USD $)In Thousands, unless otherwise specified** | Mar. 31, 2015                                                                                                                                                                                                      | Dec. 31, 2014                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            | $ 113,023fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue                                                                                                                     | $ 229,583fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue                                                                                                                     |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          | 455fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss                                                                                                                         | 694fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss                                                                                                                         |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            | 449,943fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue                                                                                                                       | 523,463fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue                                                                                                                       |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          | 17,617fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss                                                                                                                      | 23,726fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss                                                                                                                      |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              | 562,966fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal                                                                                                                                      | 753,046fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal                                                                                                                                      |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               | 18,072fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss                                                                                                                                      | 24,420fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss                                                                                                                                      |
| US Government Agencies Residential Mortgage-backed Securities [Member]                                                                                     |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            |                                                                                                                                                                                                               | 2,318fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                      |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          |                                                                                                                                                                                                               | 3fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                        |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            |                                                                                                                                                                                                               | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                          |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          |                                                                                                                                                                                                               | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                        |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              |                                                                                                                                                                                                               | 2,318fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                                     |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               |                                                                                                                                                                                                               | 3fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentAgenciesDebtSecuritiesMember                                        |
| Residential Mortgage Backed Securities [Member]                                                                                                            |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            | 84,160fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                    | 111,646fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                   |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          | 435fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                     | 419fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                     |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            | 300,792fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                   | 368,706fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                   |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          | 6,065fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                   | 9,411fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                   |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              | 384,952fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                                  | 480,352fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                                  |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               | 6,500fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                                   | 9,830fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_ResidentialMortgageBackedSecuritiesMember                                   |
| Obligations of U.S. Government-Sponsored Enterprises - Other Government-Sponsored Enterprises [Member]                                                     |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            | 27,985fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember         | 112,473fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember        |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          | 15fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember           | 229fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember          |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            | 122,833fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember        | 130,401fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember        |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          | 315fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember          | 1,079fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember        |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              | 150,818fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember                       | 242,874fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember                       |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               | 330fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember                          | 1,308fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember                        |
| Obligations of States and Political Subdivisions [Member]                                                                                                  |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            | 878fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                          | 3,146fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                        |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          | 5fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                          | 43fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                         |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                            | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                            |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                          | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                          |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              | 878fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                                         | 3,146fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                                       |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               | 5fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                                          | 43fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_USStatesAndPoliticalSubdivisionsMember                                         |
| Pooled Trust Preferred Collateralized Debt Obligations [Member]                                                                                            |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| **Schedule of Trading Securities and Other Trading Assets [Line Items]**                                                                                   |                                                                                                                                                                                                               |                                                                                                                                                                                                               |
| Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value                                                            | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember        | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthanTwelveMonthsFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember        |
| Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss                                                          | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember      | 0fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionLessthan12MonthsAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember      |
| Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value                                                            | 26,318fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember   | 24,356fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember   |
| Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss                                                          | 11,237fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember | 13,236fcf_InvestmentSecuritiesContinuousUnrealizedLossPosition12MonthsorLongerAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember |
| Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total                                                                              | 26,318fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember                  | 24,356fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionFairValueTotal/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember                  |
| Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss                                                                               | $ 11,237fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember               | $ 13,236fcf_InvestmentSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember               |

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| - Definition
Investment Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss
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No definition available.
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Investment Securities, Continuous Unrealized Loss Position, Accumulated Loss
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No definition available.
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Investment Securities, Continuous Unrealized Loss Position, Fair Value, Total
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No definition available.
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Investment Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss
+ References
No definition available.
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Investment Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value
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No definition available.
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Investment Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value
+ References
No definition available.
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