$FCF
FIRST COMMONWEALTH FINANCIAL CORP /PA/ Stock $fcf

$fcf Overview Financials Valuation SEC Filings Company Website

2020 Form 10-K Financial Statement

#000071253721000007 Filed on March 01, 2021

Income Statement

Concept	2020	2019 Q4	2019
Revenue	$301.2M		$325.3M
YoY Change	-7.4%		11.29%
Cost Of Revenue
YoY Change
Gross Profit
YoY Change
Gross Profit Margin
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$11.70M	$2.600M	$10.40M
YoY Change	12.5%	8.33%	30.0%
% of Gross Profit
Operating Expenses
YoY Change
Operating Profit
YoY Change
Interest Expense	$32.94M		$55.40M
YoY Change	-40.55%		38.38%
% of Operating Profit
Other Income/Expense, Net
YoY Change
Pretax Income	$90.20M	$33.33M	$130.8M
YoY Change	-31.06%	-2.14%	-1.45%
Income Tax	$16.76M	$6.510M	$25.52M
% Of Pretax Income	18.58%	19.53%	19.5%
Net Earnings	$73.45M	$26.82M	$105.3M
YoY Change	-30.27%	-0.67%	-2.01%
Net Earnings / Revenue	24.38%		32.38%
Basic Earnings Per Share	$0.75		$1.07
Diluted Earnings Per Share	$0.75	$272.3K	$1.07
COMMON SHARES
Basic Shares Outstanding	97.50M shares	98.32M shares	98.32M shares
Diluted Shares Outstanding	97.76M shares		98.59M shares

Balance Sheet

Concept	2020	2019 Q4	2019
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents		$121.9M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment	$125.5M	$137.3M	$137.3M
YoY Change	-8.59%	70.57%	70.56%
Goodwill		$303.3M
YoY Change		10.62%
Intangibles		$16.37M
YoY Change		25.53%
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$9.068B	$8.309B	$8.309B
YoY Change	9.14%	6.14%	6.14%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$46.80M
YoY Change
Deferred Revenue
YoY Change
Short-Term Debt	$117.4M	$201.9M	$65.70M
YoY Change	78.69%	-72.04%	-58.1%
Long-Term Debt Due	$6.400M	$6.800M	$6.800M
YoY Change	-5.88%	-5.56%	-5.56%
Total Short-Term Liabilities	$53.20M	$6.800M	$6.800M
YoY Change	682.35%	-5.56%	-5.56%
LONG-TERM LIABILITIES
Long-Term Debt	$170.6M	$170.5M	$170.5M
YoY Change	0.06%	0.12%	0.12%
Other Long-Term Liabilities	$163.4M	$139.5M	$139.5M
YoY Change	17.13%	190.63%	190.63%
Total Long-Term Liabilities	$334.0M	$310.0M	$310.0M
YoY Change	7.74%	42.01%	42.01%
TOTAL LIABILITIES
Total Short-Term Liabilities	$53.20M	$6.800M	$6.800M
Total Long-Term Liabilities	$334.0M	$310.0M	$310.0M
Total Liabilities	$8.000B	$7.253B	$7.253B
YoY Change	10.29%	5.84%	5.84%
SHAREHOLDERS EQUITY
Retained Earnings		$577.3M
YoY Change		12.89%
Common Stock		$113.9M
YoY Change		0.0%
Preferred Stock
YoY Change
Treasury Stock (at cost)		$134.9M
YoY Change		3.09%
Treasury Stock Shares		15.60M shares
Shareholders Equity	$1.069B	$1.056B	$1.056B
YoY Change
Total Liabilities & Shareholders Equity	$9.068B	$8.309B	$8.309B
YoY Change	9.14%	6.14%	6.14%

Cashflow Statement

Concept	2020	2019 Q4	2019
OPERATING ACTIVITIES
Net Income	$73.45M	$26.82M	$105.3M
YoY Change	-30.27%	-0.67%	-2.01%
Depreciation, Depletion And Amortization	$11.70M	$2.600M	$10.40M
YoY Change	12.5%	8.33%	30.0%
Cash From Operating Activities	$105.7M	$30.80M	$107.6M
YoY Change	-1.8%	-26.32%	-20.43%
INVESTING ACTIVITIES
Capital Expenditures	$7.615M	-$3.300M	$17.38M
YoY Change	-56.19%	22.22%	81.06%
Acquisitions	$0.00		-$332.5M
YoY Change	-100.0%		47058.58%
Other Investing Activities	-$475.5M	-$142.1M	$140.3M
YoY Change	-438.92%	2.3%	-141.5%
Cash From Investing Activities	-$483.1M	-$145.4M	$122.9M
YoY Change	-492.98%	2.61%	-135.35%
FINANCING ACTIVITIES
Cash Dividend Paid	$42.98M		$39.39M
YoY Change	9.11%		13.04%
Common Stock Issuance & Retirement, Net	$20.91M		$6.259M
YoY Change	234.0%		-76.1%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	$612.2M	107.7M	-$207.7M
YoY Change	-394.78%	4.87%	-201.73%
NET CHANGE
Cash From Operating Activities	$105.7M	30.80M	$107.6M
Cash From Investing Activities	-$483.1M	-145.4M	$122.9M
Cash From Financing Activities	$612.2M	107.7M	-$207.7M
Net Change In Cash	$234.7M	-6.900M	$22.91M
YoY Change	924.6%	-346.43%	-374.52%
FREE CASH FLOW
Cash From Operating Activities	$105.7M	$30.80M	$107.6M
Capital Expenditures	$7.615M	-$3.300M	$17.38M
Free Cash Flow	$98.08M	$34.10M	$90.25M
YoY Change	8.68%	-23.37%	-28.18%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2020	dei	Entity Registrant Name EntityRegistrantName	FIRST COMMONWEALTH FINANCIAL CORP /PA/
CY2020	dei	Entity Central Index Key EntityCentralIndexKey	0000712537
CY2020	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2020	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2020
CY2020	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2020	dei	Amendment Flag AmendmentFlag	false
CY2020	dei	Trading Symbol TradingSymbol	FCF
CY2021Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	96162202	shares
CY2020	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	PA
CY2020	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2020Q2	dei	Entity Public Float EntityPublicFloat	799866969	USD
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CY2020Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
CY2019Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	200000000	shares
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CY2019Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	113914902	shares
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CY2020Q4	us-gaap	Treasury Stock Shares TreasuryStockShares	17784151	shares
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CY2019Q4	us-gaap	Fair Value Concentration Of Risk Commitments FairValueConcentrationOfRiskCommitments	138000	USD
CY2020	fcf	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Includedin Earnings On Assets Held At Year End FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedinEarningsOnAssetsHeldAtYearEnd	0	USD
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CY2019	fcf	Fair Value Measurementwith Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Between Levels1 And2 FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetTransfersBetweenLevels1And2	0	USD
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CY2020	dei	Entity File Number EntityFileNumber	001-11138
CY2020	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	25-1428528
CY2020	dei	Entity Address Address Line1 EntityAddressAddressLine1	601 PHILADELPHIA STREET
CY2020	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	15701
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CY2020	dei	Entity Address City Or Town EntityAddressCityOrTown	INDIANA,
CY2020	dei	Entity Address State Or Province EntityAddressStateOrProvince	PA
CY2020	dei	City Area Code CityAreaCode	724
CY2020	dei	Local Phone Number LocalPhoneNumber	349-7220
CY2020	dei	Security12b Title Security12bTitle	COMMON STOCK, $1 PAR VALUE
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CY2020	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
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CY2020	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
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CY2018	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	252222000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	56718000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	14533000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	12531000	USD
CY2020	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	211553000	USD
CY2019	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	255329000	USD
CY2018	us-gaap	Interest Income Expense After Provision For Loan Loss InterestIncomeExpenseAfterProvisionForLoanLoss	239691000	USD
CY2020	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	70000	USD
CY2019	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	22000	USD
CY2018	us-gaap	Debt And Equity Securities Gain Loss DebtAndEquitySecuritiesGainLoss	8102000	USD
CY2020	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	9101000	USD
CY2019	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	8321000	USD
CY2018	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	7901000	USD
CY2020	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	16387000	USD
CY2019	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	18926000	USD
CY2018	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	18175000	USD
CY2020	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7850000	USD
CY2019	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7583000	USD
CY2018	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7426000	USD
CY2020	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6552000	USD
CY2019	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6002000	USD
CY2018	us-gaap	Bank Owned Life Insurance Income BankOwnedLifeInsuranceIncome	6686000	USD
CY2020	us-gaap	Gain Loss On Sale Of Mortgage Loans GainLossOnSaleOfMortgageLoans	18764000	USD
CY2019	us-gaap	Gain Loss On Sale Of Mortgage Loans GainLossOnSaleOfMortgageLoans	7765000	USD
CY2018	us-gaap	Gain Loss On Sale Of Mortgage Loans GainLossOnSaleOfMortgageLoans	5436000	USD
CY2020	us-gaap	Gain Loss On Disposition Of Other Financial Assets GainLossOnDispositionOfOtherFinancialAssets	4827000	USD
CY2019	us-gaap	Gain Loss On Disposition Of Other Financial Assets GainLossOnDispositionOfOtherFinancialAssets	4793000	USD
CY2018	us-gaap	Gain Loss On Disposition Of Other Financial Assets GainLossOnDispositionOfOtherFinancialAssets	5273000	USD
CY2020	fcf	Non Interest Income Interchange NonInterestIncomeInterchange	23966000	USD
CY2019	fcf	Non Interest Income Interchange NonInterestIncomeInterchange	21677000	USD
CY2018	fcf	Non Interest Income Interchange NonInterestIncomeInterchange	20187000	USD
CY2020	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-2521000	USD
CY2019	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-269000	USD
CY2018	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	787000	USD
CY2020	fcf	Swap Fee Income SwapFeeIncome	1588000	USD
CY2019	fcf	Swap Fee Income SwapFeeIncome	3397000	USD
CY2018	fcf	Swap Fee Income SwapFeeIncome	1874000	USD
CY2020	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	7892000	USD
CY2019	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	7268000	USD
CY2018	us-gaap	Noninterest Income Other Operating Income NoninterestIncomeOtherOperatingIncome	6790000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	94476000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	85485000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	88637000	USD
CY2020	us-gaap	Labor And Related Expense LaborAndRelatedExpense	118961000	USD
CY2019	us-gaap	Labor And Related Expense LaborAndRelatedExpense	112237000	USD
CY2018	us-gaap	Labor And Related Expense LaborAndRelatedExpense	105115000	USD
CY2020	us-gaap	Occupancy Net OccupancyNet	17647000	USD
CY2019	us-gaap	Occupancy Net OccupancyNet	18923000	USD
CY2018	us-gaap	Occupancy Net OccupancyNet	17219000	USD
CY2020	us-gaap	Equipment Expense EquipmentExpense	15393000	USD
CY2019	us-gaap	Equipment Expense EquipmentExpense	15160000	USD
CY2018	us-gaap	Equipment Expense EquipmentExpense	14247000	USD
CY2020	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	10543000	USD
CY2019	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	10692000	USD
CY2018	us-gaap	Information Technology And Data Processing InformationTechnologyAndDataProcessing	10470000	USD
CY2020	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	4679000	USD
CY2019	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	4250000	USD
CY2018	us-gaap	Marketing And Advertising Expense MarketingAndAdvertisingExpense	3956000	USD
CY2020	fcf	Shares Tax SharesTax	4500000	USD
CY2019	fcf	Shares Tax SharesTax	4602000	USD
CY2018	fcf	Shares Tax SharesTax	4875000	USD
CY2020	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	3689000	USD
CY2019	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	3344000	USD
CY2018	us-gaap	Amortization Of Intangible Assets AmortizationOfIntangibleAssets	3217000	USD
CY2020	us-gaap	Professional Fees ProfessionalFees	3886000	USD
CY2019	us-gaap	Professional Fees ProfessionalFees	4631000	USD
CY2018	us-gaap	Professional Fees ProfessionalFees	4473000	USD
CY2020	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	2699000	USD
CY2019	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	1219000	USD
CY2018	us-gaap	Federal Deposit Insurance Corporation Premium Expense FederalDepositInsuranceCorporationPremiumExpense	2007000	USD
CY2020	us-gaap	Asset Impairment Charges AssetImpairmentCharges	680000	USD
CY2019	us-gaap	Asset Impairment Charges AssetImpairmentCharges	1724000	USD
CY2018	us-gaap	Asset Impairment Charges AssetImpairmentCharges	1080000	USD
CY2020	fcf	Operational Losses OperationalLosses	1411000	USD
CY2019	fcf	Operational Losses OperationalLosses	1687000	USD
CY2018	fcf	Operational Losses OperationalLosses	1162000	USD
CY2020	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	0	USD
CY2019	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	3536000	USD
CY2018	us-gaap	Business Combination Acquisition Related Costs BusinessCombinationAcquisitionRelatedCosts	1637000	USD
CY2020	fcf	Covid19 Related Expenses COVID19RelatedExpenses	874000	USD
CY2019	fcf	Covid19 Related Expenses COVID19RelatedExpenses	0	USD
CY2018	fcf	Covid19 Related Expenses COVID19RelatedExpenses	0	USD
CY2020	fcf	Voluntary Retirement Plan Expenses VoluntaryRetirementPlanExpenses	3422000	USD
CY2019	fcf	Voluntary Retirement Plan Expenses VoluntaryRetirementPlanExpenses	0	USD
CY2018	fcf	Voluntary Retirement Plan Expenses VoluntaryRetirementPlanExpenses	0	USD
CY2020	fcf	Branch Consolidation Expense BranchConsolidationExpense	2672000	USD
CY2019	fcf	Branch Consolidation Expense BranchConsolidationExpense	0	USD
CY2018	fcf	Branch Consolidation Expense BranchConsolidationExpense	0	USD
CY2020	us-gaap	Other Noninterest Expense OtherNoninterestExpense	24770000	USD
CY2019	us-gaap	Other Noninterest Expense OtherNoninterestExpense	27960000	USD
CY2018	us-gaap	Other Noninterest Expense OtherNoninterestExpense	26098000	USD
CY2020	us-gaap	Noninterest Expense NoninterestExpense	215826000	USD
CY2019	us-gaap	Noninterest Expense NoninterestExpense	209965000	USD
CY2018	us-gaap	Noninterest Expense NoninterestExpense	195556000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	90203000	USD
CY2019	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	130849000	USD
CY2018	us-gaap	Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments	132772000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16756000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25516000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25274000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73447000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	105333000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	107498000	USD
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	97499586	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	98317787	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	99036163	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	97758965	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	98588164	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	99223513	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.75
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.07
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.09
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.07
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.08
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.44
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.40
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.35
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73447000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	105333000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	107498000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	19981000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	20625000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	2783000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	70000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	22000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	8102000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-4467000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	935000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	326000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-10000	USD
CY2020	us-gaap	Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Net Prior Service Cost Credit Before Tax DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax	-537000	USD
CY2019	us-gaap	Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Net Prior Service Cost Credit Before Tax DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax	0	USD
CY2018	us-gaap	Defined Benefit Plan Amounts Recognized In Other Comprehensive Income Net Prior Service Cost Credit Before Tax DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-155000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	-121000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Net Unamortized Gain Loss Arising During Period Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansNetUnamortizedGainLossArisingDuringPeriodBeforeTax	144000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	14752000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	21417000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax Portion Attributable To Parent OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent	-4839000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	3098000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	4497000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax Portion Attributable To Parent1 OtherComprehensiveIncomeLossTaxPortionAttributableToParent1	-1015000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	85101000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	122253000	USD
CY2018	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	103674000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73447000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	11654000	USD
CY2020	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	42982000	USD
CY2020Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	11199000	USD
CY2020	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	20905000	USD
CY2020	us-gaap	Stock Issued During Period Value Treasury Stock Reissued StockIssuedDuringPeriodValueTreasuryStockReissued	1817000	USD
CY2020	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	1120000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1068617000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	975389000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	105333000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	16920000	USD
CY2019	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	39394000	USD
CY2019	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	6259000	USD
CY2019	us-gaap	Stock Issued During Period Value Treasury Stock Reissued StockIssuedDuringPeriodValueTreasuryStockReissued	2744000	USD
CY2019	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	932000	USD
CY2017Q4	us-gaap	Stockholders Equity StockholdersEquity	888127000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	107498000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3824000	USD
CY2018	us-gaap	Dividends Common Stock Cash DividendsCommonStockCash	34849000	USD
CY2018	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	26189000	USD
CY2018	us-gaap	Stock Issued During Period Value Treasury Stock Reissued StockIssuedDuringPeriodValueTreasuryStockReissued	44026000	USD
CY2018	us-gaap	Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodValueRestrictedStockAwardNetOfForfeitures	600000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	975389000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73447000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	105333000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	107498000	USD
CY2020	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	56718000	USD
CY2019	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	14533000	USD
CY2018	us-gaap	Provision For Loan Lease And Other Losses ProvisionForLoanLeaseAndOtherLosses	12531000	USD
CY2020	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	-8217000	USD
CY2019	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	2292000	USD
CY2018	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	3473000	USD
CY2020	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	11653000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	10370000	USD
CY2018	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	8046000	USD
CY2020	fcf	Gain Loss On Securities And Other Assets GainLossOnSecuritiesAndOtherAssets	18807000	USD
CY2019	fcf	Gain Loss On Securities And Other Assets GainLossOnSecuritiesAndOtherAssets	10671000	USD
CY2018	fcf	Gain Loss On Securities And Other Assets GainLossOnSecuritiesAndOtherAssets	21540000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-6183000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-3892000	USD
CY2018	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-3083000	USD
CY2020	fcf	Earningson Bank Owned Life Insurance EarningsonBankOwnedLifeInsurance	6288000	USD
CY2019	fcf	Earningson Bank Owned Life Insurance EarningsonBankOwnedLifeInsurance	5998000	USD
CY2018	fcf	Earningson Bank Owned Life Insurance EarningsonBankOwnedLifeInsurance	5808000	USD
CY2020	us-gaap	Payments For Origination Of Mortgage Loans Held For Sale PaymentsForOriginationOfMortgageLoansHeldForSale	410715000	USD
CY2019	us-gaap	Payments For Origination Of Mortgage Loans Held For Sale PaymentsForOriginationOfMortgageLoansHeldForSale	251428000	USD
CY2018	us-gaap	Payments For Origination Of Mortgage Loans Held For Sale PaymentsForOriginationOfMortgageLoansHeldForSale	165898000	USD
CY2020	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	408877000	USD
CY2019	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	251968000	USD
CY2018	us-gaap	Proceeds From Sale Of Mortgage Loans Held For Sale ProceedsFromSaleOfMortgageLoansHeldForSale	177287000	USD
CY2020	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	10735000	USD
CY2019	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	-423000	USD
CY2018	us-gaap	Increase Decrease In Accrued Interest Receivable Net IncreaseDecreaseInAccruedInterestReceivableNet	2561000	USD
CY2020	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-879000	USD
CY2019	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	-256000	USD
CY2018	us-gaap	Increase Decrease In Interest Payable Net IncreaseDecreaseInInterestPayableNet	383000	USD
CY2020	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-887000	USD
CY2019	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	1484000	USD
CY2018	us-gaap	Increase Decrease In Accrued Income Taxes Payable IncreaseDecreaseInAccruedIncomeTaxesPayable	-1926000	USD
CY2020	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
CY2019	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	0	USD
CY2018	us-gaap	Proceeds From Equity Method Investment Dividends Or Distributions Return Of Capital ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital	9000000	USD
CY2020	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-5349000	USD
CY2019	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	14310000	USD
CY2018	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	-11695000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	105699000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	107632000	USD
CY2018	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	135263000	USD
CY2020	us-gaap	Proceeds From Sale And Maturity Of Held To Maturity Securities ProceedsFromSaleAndMaturityOfHeldToMaturitySecurities	0	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Held To Maturity Securities ProceedsFromSaleAndMaturityOfHeldToMaturitySecurities	948000	USD
CY2018	us-gaap	Proceeds From Sale And Maturity Of Held To Maturity Securities ProceedsFromSaleAndMaturityOfHeldToMaturitySecurities	0	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	118905000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	54632000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Held To Maturity Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfHeldToMaturitySecurities	47614000	USD
CY2020	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	85679000	USD
CY2019	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	200000	USD
CY2018	us-gaap	Payments To Acquire Held To Maturity Securities PaymentsToAcquireHeldToMaturitySecurities	20650000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	0	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	0	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities ProceedsFromSaleOfAvailableForSaleSecurities	15939000	USD
CY2020	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	472282000	USD
CY2019	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	189194000	USD
CY2018	us-gaap	Proceeds From Maturities Prepayments And Calls Of Available For Sale Securities ProceedsFromMaturitiesPrepaymentsAndCallsOfAvailableForSaleSecurities	140707000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	411178000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	138670000	USD
CY2018	us-gaap	Payments To Acquire Available For Sale Securities PaymentsToAcquireAvailableForSaleSecurities	331969000	USD
CY2020	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	22231000	USD
CY2019	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	36850000	USD
CY2018	us-gaap	Payments To Acquire Federal Home Loan Bank Stock PaymentsToAcquireFederalHomeLoanBankStock	52107000	USD
CY2020	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	26766000	USD
CY2019	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	52215000	USD
CY2018	us-gaap	Proceeds From Sale Of Federal Home Loan Bank Stock ProceedsFromSaleOfFederalHomeLoanBankStock	51488000	USD
CY2020	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	1444000	USD
CY2019	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	557000	USD
CY2018	us-gaap	Proceeds From Life Insurance Policies ProceedsFromLifeInsurancePolicies	2140000	USD
CY2020	us-gaap	Proceeds From Sale Of Loans Receivable ProceedsFromSaleOfLoansReceivable	41141000	USD
CY2019	us-gaap	Proceeds From Sale Of Loans Receivable ProceedsFromSaleOfLoansReceivable	37534000	USD
CY2018	us-gaap	Proceeds From Sale Of Loans Receivable ProceedsFromSaleOfLoansReceivable	40783000	USD
CY2020	us-gaap	Proceeds From Sale Of Other Productive Assets ProceedsFromSaleOfOtherProductiveAssets	5531000	USD
CY2019	us-gaap	Proceeds From Sale Of Other Productive Assets ProceedsFromSaleOfOtherProductiveAssets	6822000	USD
CY2018	us-gaap	Proceeds From Sale Of Other Productive Assets ProceedsFromSaleOfOtherProductiveAssets	4477000	USD
CY2020	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	0	USD
CY2019	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-332468000	USD
CY2018	us-gaap	Payments To Acquire Businesses Net Of Cash Acquired PaymentsToAcquireBusinessesNetOfCashAcquired	-705000	USD
CY2020	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	622504000	USD
CY2019	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	358328000	USD
CY2018	us-gaap	Payments For Proceeds From Loans And Leases PaymentsForProceedsFromLoansAndLeases	237276000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	7615000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	17380000	USD
CY2018	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	9599000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-483138000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	122942000	USD
CY2018	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-347748000	USD
CY2020	us-gaap	Increase Decrease In Federal Funds Purchased IncreaseDecreaseInFederalFundsPurchased	0	USD
CY2019	us-gaap	Increase Decrease In Federal Funds Purchased IncreaseDecreaseInFederalFundsPurchased	11000000	USD
CY2018	us-gaap	Increase Decrease In Federal Funds Purchased IncreaseDecreaseInFederalFundsPurchased	-11000000	USD
CY2020	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-84480000	USD
CY2019	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	-508970000	USD
CY2018	us-gaap	Proceeds From Repayments Of Short Term Debt ProceedsFromRepaymentsOfShortTermDebt	3357000	USD
CY2020	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	761398000	USD
CY2019	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	308783000	USD
CY2018	us-gaap	Increase Decrease In Deposits IncreaseDecreaseInDeposits	176558000	USD
CY2020	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	659000	USD
CY2019	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	634000	USD
CY2018	us-gaap	Repayments Of Other Long Term Debt RepaymentsOfOtherLongTermDebt	23598000	USD
CY2020	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	0	USD
CY2019	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	50000000	USD
CY2018	us-gaap	Proceeds From Issuance Of Long Term Debt ProceedsFromIssuanceOfLongTermDebt	98026000	USD
CY2020	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	430000	USD
CY2019	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	402000	USD
CY2018	us-gaap	Repayments Of Long Term Capital Lease Obligations RepaymentsOfLongTermCapitalLeaseObligations	373000	USD
CY2020	us-gaap	Payments Of Dividends PaymentsOfDividends	42982000	USD
CY2019	us-gaap	Payments Of Dividends PaymentsOfDividends	39394000	USD
CY2020	fcf	Useful Life Of Capitalized Software UsefulLifeOfCapitalizedSoftware	P7Y
CY2018	us-gaap	Payments Of Dividends PaymentsOfDividends	34849000	USD
CY2020	us-gaap	Proceeds From Sale Of Treasury Stock ProceedsFromSaleOfTreasuryStock	222000	USD
CY2019	us-gaap	Proceeds From Sale Of Treasury Stock ProceedsFromSaleOfTreasuryStock	211000	USD
CY2018	us-gaap	Proceeds From Sale Of Treasury Stock ProceedsFromSaleOfTreasuryStock	208000	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	20905000	USD
CY2019	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	6259000	USD
CY2018	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	26189000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	612164000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-207665000	USD
CY2018	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	204140000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	234725000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	22909000	USD
CY2018	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-8345000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	121856000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	98947000	USD
CY2017Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	107292000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	356581000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	121856000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	98947000	USD
CY2020Q4	fcf	Numberof Countiesin Which Entity Provides Services NumberofCountiesinWhichEntityProvidesServices	26	county
CY2020	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	1	Segment
CY2020	fcf	Percentage Of Ownership In Equity Investments PercentageOfOwnershipInEquityInvestments	0.20
CY2020	us-gaap	Derivatives Methods Of Accounting Hedging Derivatives DerivativesMethodsOfAccountingHedgingDerivatives	<div style="margin-top:14pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Derivatives and Hedging Activities</span></div><div style="margin-top:5pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">First Commonwealth accounts for derivative instruments and hedging activities in accordance with FASB ASC Topic 815, “Derivatives and Hedging.” All derivatives are evaluated at inception as to whether or not they are hedging or non-hedging activities, and appropriate documentation is maintained to support the final determination. First Commonwealth recognizes all derivatives as either assets or liabilities on the Consolidated Statements of Financial Condition and measures those instruments at fair value. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in other comprehensive income ("OCI"). When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in the Consolidated Statement of Income.</span></div><div style="margin-top:9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">When First Commonwealth purchases a portion of a commercial loan that has an existing interest rate swap, it enters a Risk Participation Agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to First Commonwealth as a result of the risk participation agreement is offset by credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties.</span></div><div style="margin-top:9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">Management periodically reviews contracts from various functional areas of First Commonwealth to identify potential derivatives embedded within selected contracts. As of December 31, 2020, First Commonwealth has interest rate derivative positions that are designated as hedging instruments and others that are not designated as hedging instruments. See Note 7, “Derivatives,” for a description of these instruments.</span></div>
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	19981000	USD
CY2020	fcf	Loans Past Due Days LoansPastDueDays	P90D
CY2020	fcf	Loans Past Due Days LoansPastDueDays	P90D
CY2020	fcf	Excess Impaired Loan Credit ExcessImpairedLoanCredit	250000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	4196000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	15785000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	20625000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	4331000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	16294000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodBeforeTax	2783000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	585000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	2198000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	70000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	15000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	55000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	22000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	5000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	17000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax	8102000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	1701000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	6401000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	19911000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	4181000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	15730000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	20603000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	4326000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	16277000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Before Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentBeforeTax	-5319000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	-1116000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Adjustment Net Of Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax	-4203000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	-4467000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	-938000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	-3529000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	935000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	196000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	739000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Before Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax	326000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax	68000	USD
CY2018	us-gaap	Other Comprehensive Income Unrealized Gain Loss On Derivatives Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax	258000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax	-10000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax	-3000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci On Derivatives Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax	-7000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	-4467000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesTax	-938000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	-3529000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	935000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesTax	196000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	739000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Before Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesBeforeTax	336000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesTax	71000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Derivatives Qualifying As Hedges Net Of Tax OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax	265000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	-537000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	113000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Before Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	0	USD
CY2019	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax	0	USD
CY2018	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	0	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	155000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	32000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	123000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	121000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	25000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	96000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Before Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax	-144000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossTax	-30000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	-114000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	692000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	145000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	547000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	121000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	25000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	96000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Before Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax	-144000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax	-30000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Pension And Other Postretirement Benefit Plans Adjustment Net Of Tax OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax	-114000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	14752000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	3098000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	11654000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	21417000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	4497000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	16920000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Tax OtherComprehensiveIncomeLossBeforeTax	-4839000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Amortization Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Prior Service Cost Credit Net Of Tax OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax	424000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Tax OtherComprehensiveIncomeLossTax	-1015000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3824000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	12256000	USD
CY2020	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	55000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci Pension And Other Postretirement Benefit Plans For Net Gain Loss Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax	123000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	11654000	USD
CY2020Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	17233000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-11341000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	17033000	USD
CY2019	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	17000	USD
CY2019	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	96000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	16920000	USD
CY2017Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-6173000	USD
CY2017Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	-1344000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Before Reclassifications Net Of Tax OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax	2456000	USD
CY2018	us-gaap	Reclassification From Accumulated Other Comprehensive Income Current Period Net Of Tax ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax	6394000	USD
CY2018	us-gaap	Other Comprehensive Income Defined Benefit Plans Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent	-114000	USD
CY2018	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-3824000	USD
CY2018Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-11341000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	33964000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	56005000	USD
CY2018	us-gaap	Interest Paid Net InterestPaidNet	40071000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	25914000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	21787000	USD
CY2018	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	23826000	USD
CY2020	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	3865000	USD
CY2019	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	4723000	USD
CY2018	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	4334000	USD
CY2020	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	37305000	USD
CY2019	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	30359000	USD
CY2018	us-gaap	Transfer Of Portfolio Loans And Leases To Held For Sale1 TransferOfPortfolioLoansAndLeasesToHeldForSale1	37367000	USD
CY2020	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	4335000	USD
CY2019	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	482000	USD
CY2018	us-gaap	Transfer Of Loans Held For Sale To Portfolio Loans1 TransferOfLoansHeldForSaleToPortfolioLoans1	0	USD
CY2020	fcf	Gross Increase Decrease In Market Value Adjustment To Securities Available For Sale GrossIncreaseDecreaseInMarketValueAdjustmentToSecuritiesAvailableForSale	19911000	USD
CY2019	fcf	Gross Increase Decrease In Market Value Adjustment To Securities Available For Sale GrossIncreaseDecreaseInMarketValueAdjustmentToSecuritiesAvailableForSale	20604000	USD
CY2018	fcf	Gross Increase Decrease In Market Value Adjustment To Securities Available For Sale GrossIncreaseDecreaseInMarketValueAdjustmentToSecuritiesAvailableForSale	-5319000	USD
CY2020	fcf	Credit Valuation Gain Losson Derivative Asset Gross CreditValuationGainLossonDerivativeAssetGross	-4467000	USD
CY2019	fcf	Credit Valuation Gain Losson Derivative Asset Gross CreditValuationGainLossonDerivativeAssetGross	935000	USD
CY2018	fcf	Credit Valuation Gain Losson Derivative Asset Gross CreditValuationGainLossonDerivativeAssetGross	336000	USD
CY2020	fcf	Investments Committedto Purchase Not Yet Paid InvestmentsCommittedtoPurchaseNotYetPaid	-34185000	USD
CY2019	fcf	Investments Committedto Purchase Not Yet Paid InvestmentsCommittedtoPurchaseNotYetPaid	25484000	USD
CY2018	fcf	Investments Committedto Purchase Not Yet Paid InvestmentsCommittedtoPurchaseNotYetPaid	0	USD
CY2020	fcf	Increasein Commitmentto Limited Partnership IncreaseinCommitmenttoLimitedPartnership	0	USD
CY2019	fcf	Increasein Commitmentto Limited Partnership IncreaseinCommitmenttoLimitedPartnership	1469000	USD
CY2018	fcf	Increasein Commitmentto Limited Partnership IncreaseinCommitmenttoLimitedPartnership	0	USD
CY2020	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	0	USD
CY2019	fcf	Weighted Average Numberof Shares Deferred Compensation Plans WeightedAverageNumberofSharesDeferredCompensationPlans	37496	shares
CY2019	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	361595000	USD
CY2018	us-gaap	Noncash Or Part Noncash Acquisition Value Of Assets Acquired1 NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1	21834000	USD
CY2020	fcf	Proceedsfrom Life Insurance Policy Not Received ProceedsfromLifeInsurancePolicyNotReceived	-384000	USD
CY2019	fcf	Proceedsfrom Life Insurance Policy Not Received ProceedsfromLifeInsurancePolicyNotReceived	484000	USD
CY2018	fcf	Proceedsfrom Life Insurance Policy Not Received ProceedsfromLifeInsurancePolicyNotReceived	0	USD
CY2020	fcf	Noncash Transactions Stock Issued During Period Value NoncashTransactionsStockIssuedDuringPeriodValue	1594000	USD
CY2019	fcf	Noncash Transactions Stock Issued During Period Value NoncashTransactionsStockIssuedDuringPeriodValue	2531000	USD
CY2018	fcf	Noncash Transactions Stock Issued During Period Value NoncashTransactionsStockIssuedDuringPeriodValue	2257000	USD
CY2020	fcf	Weighted Average Number Of Shares Issued Basic And Diluted WeightedAverageNumberOfSharesIssuedBasicAndDiluted	113914902	shares
CY2019	fcf	Weighted Average Number Of Shares Issued Basic And Diluted WeightedAverageNumberOfSharesIssuedBasicAndDiluted	113914902	shares
CY2018	fcf	Weighted Average Number Of Shares Issued Basic And Diluted WeightedAverageNumberOfSharesIssuedBasicAndDiluted	113914902	shares
CY2020	us-gaap	Weighted Average Number Of Shares Treasury Stock WeightedAverageNumberOfSharesTreasuryStock	16254304	shares
CY2019	us-gaap	Weighted Average Number Of Shares Treasury Stock WeightedAverageNumberOfSharesTreasuryStock	15447299	shares
CY2018	us-gaap	Weighted Average Number Of Shares Treasury Stock WeightedAverageNumberOfSharesTreasuryStock	14747687	shares
CY2020	fcf	Weighted Average Numberof Shares Deferred Compensation Plans WeightedAverageNumberofSharesDeferredCompensationPlans	42751	shares
CY2018	fcf	Weighted Average Numberof Shares Deferred Compensation Plans WeightedAverageNumberofSharesDeferredCompensationPlans	37411	shares
CY2020	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	118261	shares
CY2019	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	112320	shares
CY2018	us-gaap	Weighted Average Number Of Shares Contingently Issuable WeightedAverageNumberOfSharesContingentlyIssuable	93641	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	97499586	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	98317787	shares
CY2018	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	99036163	shares
CY2020	fcf	Weighted Average Number Of Additional Shares Non Vested WeightedAverageNumberOfAdditionalSharesNonVested	203836	shares
CY2019	fcf	Weighted Average Number Of Additional Shares Non Vested WeightedAverageNumberOfAdditionalSharesNonVested	231957	shares
CY2018	fcf	Weighted Average Number Of Additional Shares Non Vested WeightedAverageNumberOfAdditionalSharesNonVested	149939	shares
CY2020	fcf	Weighted Average Number Of Additional Shares Deferred Compensation Plan WeightedAverageNumberOfAdditionalSharesDeferredCompensationPlan	55543	shares
CY2019	fcf	Weighted Average Number Of Additional Shares Deferred Compensation Plan WeightedAverageNumberOfAdditionalSharesDeferredCompensationPlan	38420	shares
CY2018	fcf	Weighted Average Number Of Additional Shares Deferred Compensation Plan WeightedAverageNumberOfAdditionalSharesDeferredCompensationPlan	37411	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	97758965	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	98588164	shares
CY2018	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	99223513	shares
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.75
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.07
CY2018	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.09
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.75
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.07
CY2018	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.08
CY2020Q4	fcf	Average Reserve Balances With Federal Reserve Bank AverageReserveBalancesWithFederalReserveBank	173200000	USD
CY2019Q4	fcf	Average Reserve Balances With Federal Reserve Bank AverageReserveBalancesWithFederalReserveBank	14700000	USD
CY2020Q4	fcf	Numberof Participation Agreements Interest Rate Derivatives Heldasa Participant NumberofParticipationAgreementsInterestRateDerivativesHeldasaParticipant	36	Derivative
CY2020Q4	us-gaap	Number Of Interest Rate Derivatives Held NumberOfInterestRateDerivativesHeld	14	Derivative
CY2020Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	805515000	USD
CY2020	us-gaap	Available For Sale Securities Gross Unrealized Gains AvailableForSaleSecuritiesGrossUnrealizedGains	25708000	USD
CY2020	us-gaap	Available For Sale Securities Gross Unrealized Loss AvailableForSaleSecuritiesGrossUnrealizedLoss	0	USD
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	831223000	USD
CY2019Q4	us-gaap	Available For Sale Securities Amortized Cost AvailableForSaleSecuritiesAmortizedCost	896495000	USD
CY2019	us-gaap	Available For Sale Securities Gross Unrealized Gains AvailableForSaleSecuritiesGrossUnrealizedGains	8906000	USD
CY2019	us-gaap	Available For Sale Securities Gross Unrealized Loss AvailableForSaleSecuritiesGrossUnrealizedLoss	3109000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	902292000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearAmortizedCost	104995000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Within One Year Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue	105015000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsAmortizedCost	19349000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After One Through Five Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	20395000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsAmortizedCost	10747000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Five Through Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	11370000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsAmortizedCost	0	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities After Ten Years Fair Value AvailableForSaleSecuritiesDebtMaturitiesAfterTenYearsFairValue	0	USD
CY2020Q4	fcf	Available For Sale Securities Debt Maturities Gross Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesGrossAmortizedCost	135091000	USD
CY2020Q4	fcf	Available For Sale Securities Debt Maturities Gross Estimated Fair Value AvailableForSaleSecuritiesDebtMaturitiesGrossEstimatedFairValue	136780000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	805515000	USD
CY2020Q4	fcf	Available For Sale Securities Debt Maturities Estimated Fair Value AvailableForSaleSecuritiesDebtMaturitiesEstimatedFairValue	831223000	USD
CY2020	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	0	USD
CY2019	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	948000	USD
CY2018	us-gaap	Proceeds From Sale Of Available For Sale Securities Debt ProceedsFromSaleOfAvailableForSaleSecuritiesDebt	15939000	USD
CY2020	fcf	Net Gains And Impairment NetGainsAndImpairment	70000	USD
CY2019	fcf	Net Gains And Impairment NetGainsAndImpairment	22000	USD
CY2018	fcf	Net Gains And Impairment NetGainsAndImpairment	8102000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	361844000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	8017000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	10000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	369851000	USD
CY2019Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	337123000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Gain HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingGain	2073000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Accumulated Unrecognized Holding Loss HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss	478000	USD
CY2019Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	338718000	USD
CY2020Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	10600000	USD
CY2019Q4	us-gaap	Federal Home Loan Bank Stock FederalHomeLoanBankStock	15100000	USD
CY2020Q4	us-gaap	Equity Securities Fv Ni EquitySecuritiesFvNi	1700000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearNetCarryingAmount	2500000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Within One Year Fair Value HeldToMaturitySecuritiesDebtMaturitiesWithinOneYearFairValue	2525000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsNetCarryingAmount	7669000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After One Through Five Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterOneThroughFiveYearsFairValue	7742000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsNetCarryingAmount	20126000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Five Through Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterFiveThroughTenYearsFairValue	20689000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Net Carrying Amount HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsNetCarryingAmount	4896000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities After Ten Years Fair Value HeldToMaturitySecuritiesDebtMaturitiesAfterTenYearsFairValue	4940000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	35191000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	35896000	USD
CY2020Q4	us-gaap	Held To Maturity Securities HeldToMaturitySecurities	361844000	USD
CY2020Q4	us-gaap	Held To Maturity Securities Fair Value HeldToMaturitySecuritiesFairValue	369851000	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position Fair Value SecuritiesContinuousUnrealizedLossPositionFairValue	3755000	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value SecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	3755000	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses SecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses	10000	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position Twelve Monthsor Longer Fair Value SecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue	0	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	0	USD
CY2020Q4	fcf	Securities Continuous Unrealized Loss Position Aggregate Losses SecuritiesContinuousUnrealizedLossPositionAggregateLosses	10000	USD
CY2020Q4	us-gaap	Availableforsale Securities In Unrealized Loss Positions Qualitative Disclosure Number Of Positions1 AvailableforsaleSecuritiesInUnrealizedLossPositionsQualitativeDisclosureNumberOfPositions1	2	Security
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position Less Than Twelve Months Fair Value SecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue	166470000	USD
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position Less Than12 Months Aggregate Losses SecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses	637000	USD
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position Twelve Monthsor Longer Fair Value SecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue	235380000	USD
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position12 Months Or Longer Aggregate Losses SecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses	2950000	USD
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position Fair Value SecuritiesContinuousUnrealizedLossPositionFairValue	401850000	USD
CY2019Q4	fcf	Securities Continuous Unrealized Loss Position Aggregate Losses SecuritiesContinuousUnrealizedLossPositionAggregateLosses	3587000	USD
CY2018Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	0	USD
CY2017Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	12208000	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions No Previous Impairment OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment	0	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions No Previous Impairment OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsNoPreviousImpairment	0	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	0	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Additions Additional Credit Losses OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses	0	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Cash Flows OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsCashFlows	0	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Cash Flows OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsCashFlows	223000	USD
CY2019	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Securities Sold OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold	0	USD
CY2018	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Reductions Securities Sold OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold	9164000	USD
CY2019	fcf	Otherthan Temporary Impairment Credit Losses Recognizedin Earnings Reductions Securities Called OtherthanTemporaryImpairmentCreditLossesRecognizedinEarningsReductionsSecuritiesCalled	0	USD
CY2018	fcf	Otherthan Temporary Impairment Credit Losses Recognizedin Earnings Reductions Securities Called OtherthanTemporaryImpairmentCreditLossesRecognizedinEarningsReductionsSecuritiesCalled	2821000	USD
CY2019Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	0	USD
CY2018Q4	us-gaap	Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld	0	USD
CY2020Q4	fcf	Unearned Deferred Fees Costs On Loans UnearnedDeferredFeesCostsOnLoans	-6000000.0	USD
CY2019Q4	fcf	Unearned Deferred Fees Costs On Loans UnearnedDeferredFeesCostsOnLoans	-2800000	USD
CY2020Q4	us-gaap	Unearned Premiums UnearnedPremiums	7000000.0	USD
CY2019Q4	us-gaap	Unearned Premiums UnearnedPremiums	8500000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	6761183000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	6189148000	USD
CY2020	fcf	Forecasted Value National Unemployment Percent ForecastedValueNationalUnemploymentPercent	0.0668
CY2020Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	6761183000	USD
CY2020Q4	us-gaap	Notes Receivable Gross NotesReceivableGross	6761183000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	19300000	USD
CY2019	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	12300000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Past Due FinancingReceivableRecordedInvestmentPastDue	57702000	USD
CY2020Q4	us-gaap	Financing Receivable Recorded Investment Current FinancingReceivableRecordedInvestmentCurrent	6703481000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Gross Carrying Amount LoansAndLeasesReceivableGrossCarryingAmount	6761183000	USD
CY2020	fcf	Non Accrual Status Of Loans After Number Of Days Past Due NonAccrualStatusOfLoansAfterNumberOfDaysPastDue	P90D
CY2020Q4	us-gaap	Impaired Financing Receivable Recorded Investment ImpairedFinancingReceivableRecordedInvestment	54053000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Unpaid Principal Balance ImpairedFinancingReceivableUnpaidPrincipalBalance	65331000	USD
CY2020Q4	us-gaap	Impaired Financing Receivable Related Allowance ImpairedFinancingReceivableRelatedAllowance	4906000	USD
CY2020	us-gaap	Impaired Financing Receivable Average Recorded Investment ImpairedFinancingReceivableAverageRecordedInvestment	50728000	USD
CY2020	us-gaap	Impaired Financing Receivable Interest Income Accrual Method ImpairedFinancingReceivableInterestIncomeAccrualMethod	639000	USD
CY2020Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Accrual Status FinancingReceivableTroubledDebtRestructuredLoansAccrualStatus	8512000	USD
CY2019Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Accrual Status FinancingReceivableTroubledDebtRestructuredLoansAccrualStatus	7542000	USD
CY2018Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Accrual Status FinancingReceivableTroubledDebtRestructuredLoansAccrualStatus	8757000	USD
CY2020Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Nonaccrual Status FinancingReceivableTroubledDebtRestructuredLoansNonaccrualStatus	14740000	USD
CY2019Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Nonaccrual Status FinancingReceivableTroubledDebtRestructuredLoansNonaccrualStatus	6037000	USD
CY2018Q4	fcf	Financing Receivable Troubled Debt Restructured Loans Nonaccrual Status FinancingReceivableTroubledDebtRestructuredLoansNonaccrualStatus	11761000	USD
CY2020Q4	fcf	Troubled Debt Restructuring Loans TroubledDebtRestructuringLoans	23252000	USD
CY2019Q4	fcf	Troubled Debt Restructuring Loans TroubledDebtRestructuringLoans	13579000	USD
CY2018Q4	fcf	Troubled Debt Restructuring Loans TroubledDebtRestructuringLoans	20518000	USD
CY2020Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	60000	USD
CY2019Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	60000	USD
CY2018Q4	us-gaap	Letters Of Credit Outstanding Amount LettersOfCreditOutstandingAmount	60000	USD
CY2020Q4	fcf	Unused Line Of Credit Troubled Debt Restructured UnusedLineOfCreditTroubledDebtRestructured	11000	USD
CY2019Q4	fcf	Unused Line Of Credit Troubled Debt Restructured UnusedLineOfCreditTroubledDebtRestructured	163000	USD
CY2018Q4	fcf	Unused Line Of Credit Troubled Debt Restructured UnusedLineOfCreditTroubledDebtRestructured	1027000	USD
CY2020Q4	fcf	Commitments Net CommitmentsNet	71000	USD
CY2019Q4	fcf	Commitments Net CommitmentsNet	223000	USD
CY2020	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	41	Contract
CY2018Q4	fcf	Commitments Net CommitmentsNet	1087000	USD
CY2020	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	14874000	USD
CY2020Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	13969000	USD
CY2020	fcf	Financing Receivable Troubled Debt Restructuring Specific Reserve FinancingReceivableTroubledDebtRestructuringSpecificReserve	636000	USD
CY2019	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	38	Contract
CY2019	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	8302000	USD
CY2019Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	1928000	USD
CY2019	fcf	Financing Receivable Troubled Debt Restructuring Specific Reserve FinancingReceivableTroubledDebtRestructuringSpecificReserve	0	USD
CY2018	us-gaap	Financing Receivable Modifications Number Of Contracts2 FinancingReceivableModificationsNumberOfContracts2	58	Contract
CY2018	us-gaap	Financing Receivable Modifications Pre Modification Recorded Investment2 FinancingReceivableModificationsPreModificationRecordedInvestment2	11281000	USD
CY2018Q4	us-gaap	Financing Receivable Modifications Recorded Investment FinancingReceivableModificationsRecordedInvestment	8829000	USD
CY2018	fcf	Financing Receivable Troubled Debt Restructuring Specific Reserve FinancingReceivableTroubledDebtRestructuringSpecificReserve	0	USD
CY2020	fcf	Loans With Modifications To Rate And Payment Due To Reamortization LoansWithModificationsToRateAndPaymentDueToReamortization	800000	USD
CY2019	fcf	Loans With Modifications To Rate And Payment Due To Reamortization LoansWithModificationsToRateAndPaymentDueToReamortization	800000	USD
CY2018	fcf	Loans With Modifications To Rate And Payment Due To Reamortization LoansWithModificationsToRateAndPaymentDueToReamortization	300000	USD
CY2020	fcf	Tdr Default Days TdrDefaultDays	P90D
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	3	loan
CY2020	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	108000	USD
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	0	loan
CY2019	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	0	USD
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Number Of Contracts1 FinancingReceivableModificationsSubsequentDefaultNumberOfContracts1	1	loan
CY2018	us-gaap	Financing Receivable Modifications Subsequent Default Recorded Investment1 FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1	49000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	51637000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Write Offs FinancingReceivableAllowanceForCreditLossesWriteOffs	19250000	USD
CY2020	us-gaap	Financing Receivable Allowance For Credit Losses Recovery FinancingReceivableAllowanceForCreditLossesRecovery	2057000	USD
CY2020	us-gaap	Provision For Loan And Lease Losses ProvisionForLoanAndLeaseLosses	53472000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	101309000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	101309000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	4906000	USD
CY2020Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	96403000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	51637000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	2432000	USD
CY2019Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	49205000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	6189148000	USD
CY2019Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	17833000	USD
CY2019Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	6171315000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses FinancingReceivableAllowanceForCreditLosses	47764000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses Individually Evaluated For Impairment1 FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1	1631000	USD
CY2018Q4	us-gaap	Financing Receivable Allowance For Credit Losses Collectively Evaluated For Impairment FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment	46133000	USD
CY2018Q4	us-gaap	Loans And Leases Receivable Net Of Deferred Income LoansAndLeasesReceivableNetOfDeferredIncome	5774139000	USD
CY2018Q4	us-gaap	Financing Receivable Individually Evaluated For Impairment FinancingReceivableIndividuallyEvaluatedForImpairment	21088000	USD
CY2018Q4	us-gaap	Financing Receivable Collectively Evaluated For Impairment FinancingReceivableCollectivelyEvaluatedForImpairment	5753051000	USD
CY2020Q4	fcf	Notional Amount Of Financial Standby Letters Of Credit NotionalAmountOfFinancialStandbyLettersOfCredit	2600000	USD
CY2020Q4	fcf	Notional Amount Of Performance Standby Letters Of Credit NotionalAmountOfPerformanceStandbyLettersOfCredit	300000	USD
CY2020Q4	fcf	Notional Amount Of Commercial Letters Of Credit NotionalAmountOfCommercialLettersOfCredit	0	USD
CY2020Q4	us-gaap	Fair Value Concentration Of Risk Commitments FairValueConcentrationOfRiskCommitments	100000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	46819000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	291264000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	294188000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	165747000	USD
CY2019Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	156920000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	125517000	USD
CY2019Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	137268000	USD
CY2020Q4	fcf	Property Plant And Equipment Net Available For Sale PropertyPlantAndEquipmentNetAvailableForSale	2600000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	42617000	USD
CY2019Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	48642000	USD
CY2019Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	52894000	USD
CY2020	us-gaap	Operating Lease Cost OperatingLeaseCost	5930000	USD
CY2019	us-gaap	Operating Lease Cost OperatingLeaseCost	5328000	USD
CY2020Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P14Y9M29D
CY2019Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P15Y3M7D
CY2020Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0342	Rate
CY2019Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0343	Rate
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	5979000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	4656000	USD
CY2020	us-gaap	Gain Loss On Termination Of Lease GainLossOnTerminationOfLease	700000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due Current OperatingLeasesFutureMinimumPaymentsDueCurrent	4765000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Two Years OperatingLeasesFutureMinimumPaymentsDueInTwoYears	4653000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Three Years OperatingLeasesFutureMinimumPaymentsDueInThreeYears	4533000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Four Years OperatingLeasesFutureMinimumPaymentsDueInFourYears	4399000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due In Five Years OperatingLeasesFutureMinimumPaymentsDueInFiveYears	4174000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due Thereafter OperatingLeasesFutureMinimumPaymentsDueThereafter	38325000	USD
CY2020Q4	us-gaap	Operating Leases Future Minimum Payments Due OperatingLeasesFutureMinimumPaymentsDue	60849000	USD
CY2020Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	14030000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	46819000	USD
CY2020	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	6700000	USD
CY2019	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4900000	USD
CY2018	us-gaap	Lease And Rental Expense LeaseAndRentalExpense	4100000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	303300000	USD
CY2020	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	24856000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13223000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	11633000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Gross FiniteLivedIntangibleAssetsGross	28126000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Accumulated Amortization FiniteLivedIntangibleAssetsAccumulatedAmortization	13100000	USD
CY2019Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	15026000	USD
CY2020Q4	us-gaap	Servicing Asset ServicingAsset	1900000	USD
CY2019Q4	us-gaap	Servicing Asset ServicingAsset	1300000	USD
CY2020	us-gaap	Servicing Asset At Amortized Value Amortization1 ServicingAssetAtAmortizedValueAmortization1	300000	USD
CY2019	us-gaap	Servicing Asset At Amortized Value Amortization1 ServicingAssetAtAmortizedValueAmortization1	200000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Next Twelve Months FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths	2946000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Two FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo	2502000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Three FiniteLivedIntangibleAssetsAmortizationExpenseYearThree	2060000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Four FiniteLivedIntangibleAssetsAmortizationExpenseYearFour	1619000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense Year Five FiniteLivedIntangibleAssetsAmortizationExpenseYearFive	1181000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Amortization Expense After Year Five FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive	1325000	USD
CY2020Q4	us-gaap	Finite Lived Intangible Assets Net FiniteLivedIntangibleAssetsNet	11633000	USD
CY2020Q4	us-gaap	Interest Bearing Domestic Deposit Demand InterestBearingDomesticDepositDemand	250353000	USD
CY2019Q4	us-gaap	Interest Bearing Domestic Deposit Demand InterestBearingDomesticDepositDemand	254981000	USD
CY2020Q4	fcf	Savings Deposits SavingsDeposits	4305391000	USD
CY2019Q4	fcf	Savings Deposits SavingsDeposits	3896536000	USD
CY2020Q4	us-gaap	Time Deposits TimeDeposits	562964000	USD
CY2019Q4	us-gaap	Time Deposits TimeDeposits	835851000	USD
CY2020Q4	us-gaap	Interest Bearing Deposit Liabilities Domestic InterestBearingDepositLiabilitiesDomestic	5118708000	USD
CY2019Q4	us-gaap	Interest Bearing Deposit Liabilities Domestic InterestBearingDepositLiabilitiesDomestic	4987368000	USD
CY2020Q4	us-gaap	Interest Bearing Domestic Deposit Money Market InterestBearingDomesticDepositMoneyMarket	1200000000	USD
CY2019Q4	us-gaap	Interest Bearing Domestic Deposit Money Market InterestBearingDomesticDepositMoneyMarket	1100000000	USD
CY2020Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	700000	USD
CY2019Q4	us-gaap	Deposit Liabilities Reclassified As Loans Receivable1 DepositLiabilitiesReclassifiedAsLoansReceivable1	900000	USD
CY2020Q4	fcf	T Ime Deposits250000or More TImeDeposits250000orMore	93100000	USD
CY2019Q4	fcf	T Ime Deposits250000or More TImeDeposits250000orMore	143900000	USD
CY2020	fcf	Interest Expense Time Deposits250000or More InterestExpenseTimeDeposits250000orMore	2000000.0	USD
CY2019	fcf	Interest Expense Time Deposits250000or More InterestExpenseTimeDeposits250000orMore	3300000	USD
CY2018	fcf	Interest Expense Time Deposits250000or More InterestExpenseTimeDeposits250000orMore	1600000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year One TimeDepositMaturitiesYearOne	419197000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Two TimeDepositMaturitiesYearTwo	88783000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Three TimeDepositMaturitiesYearThree	22997000	USD
CY2020Q4	us-gaap	Time Deposit Maturities Year Four TimeDepositMaturitiesYearFour	16222000	USD
CY2020Q4	us-gaap	Time Deposit Maturities After Year Five TimeDepositMaturitiesAfterYearFive	15765000	USD
CY2020Q4	us-gaap	Time Deposits TimeDeposits	562964000	USD
CY2020Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	117373000	USD
CY2020	us-gaap	Shortterm Debt Average Outstanding Amount ShorttermDebtAverageOutstandingAmount	142634000	USD
CY2020Q4	us-gaap	Short Term Debt Weighted Average Interest Rate ShortTermDebtWeightedAverageInterestRate	0.0049
CY2019Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	201853000	USD
CY2019	us-gaap	Shortterm Debt Average Outstanding Amount ShorttermDebtAverageOutstandingAmount	391547000	USD
CY2019Q4	us-gaap	Short Term Debt Weighted Average Interest Rate ShortTermDebtWeightedAverageInterestRate	0.0212
CY2018Q4	us-gaap	Short Term Borrowings ShortTermBorrowings	721823000	USD
CY2018	us-gaap	Shortterm Debt Average Outstanding Amount ShorttermDebtAverageOutstandingAmount	618957000	USD
CY2018Q4	us-gaap	Short Term Debt Weighted Average Interest Rate ShortTermDebtWeightedAverageInterestRate	0.0174
CY2020	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	704000	USD
CY2019	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	8298000	USD
CY2018	us-gaap	Interest Expense Short Term Borrowings InterestExpenseShortTermBorrowings	10741000	USD
CY2020Q4	us-gaap	Subordinated Debt SubordinatedDebt	170612000	USD
CY2019Q4	us-gaap	Subordinated Debt SubordinatedDebt	170450000	USD
CY2020Q4	fcf	Numberof Trusts NumberofTrusts	2	trust
CY2020Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	56258000	USD
CY2019Q4	us-gaap	Other Long Term Debt OtherLongTermDebt	56917000	USD
CY2020	fcf	Percentage Of Securities Priced For Each Quarter PercentageOfSecuritiesPricedForEachQuarter	1
CY2020Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	831223000	USD
CY2020Q4	us-gaap	Other Investments OtherInvestments	12227000	USD
CY2020Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	33436000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Fair Value Disclosure PropertyPlantAndEquipmentFairValueDisclosure	442000	USD
CY2020Q4	us-gaap	Other Assets Fair Value Disclosure OtherAssetsFairValueDisclosure	60981000	USD
CY2020Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	938309000	USD
CY2020Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	61308000	USD
CY2020Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	61308000	USD
CY2019Q4	us-gaap	Available For Sale Securities AvailableForSaleSecurities	902292000	USD
CY2019Q4	us-gaap	Other Investments OtherInvestments	16761000	USD
CY2019Q4	us-gaap	Loans Held For Sale Fair Value Disclosure LoansHeldForSaleFairValueDisclosure	15989000	USD
CY2019Q4	us-gaap	Other Assets Fair Value Disclosure OtherAssetsFairValueDisclosure	27689000	USD
CY2019Q4	us-gaap	Assets Fair Value Disclosure AssetsFairValueDisclosure	962731000	USD
CY2019Q4	us-gaap	Other Liabilities Fair Value Disclosure OtherLiabilitiesFairValueDisclosure	21469000	USD
CY2019Q4	us-gaap	Liabilities Fair Value Disclosure LiabilitiesFairValueDisclosure	21469000	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	7465000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	824000	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Issues FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2020	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2020Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	8289000	USD
CY2018Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	4366000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings1 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1	198000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Other Comprehensive Income Loss FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Purchases FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases	2956000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Issues FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Sales FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Settlements FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements	55000	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Out Of Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2019	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Transfers Into Level3 FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3	0	USD
CY2019Q4	us-gaap	Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Value FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue	7465000	USD
CY2020Q4	fcf	Impaired Loans Fair Value Non Collection ImpairedLoansFairValueNonCollection	250000	USD
CY2020Q4	fcf	Updated Appraisal Requirement Floor UpdatedAppraisalRequirementFloor	250000	USD
CY2020Q4	fcf	Updated Appraisal Requirement Floor UpdatedAppraisalRequirementFloor	250000	USD
CY2020Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	1200000	USD
CY2020Q4	us-gaap	Fair Value Concentration Of Risk Commitments FairValueConcentrationOfRiskCommitments	100000	USD
CY2020	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	21629000	USD
CY2019	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	22942000	USD
CY2019	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	282000	USD
CY2018	us-gaap	Current Federal Tax Expense Benefit CurrentFederalTaxExpenseBenefit	21330000	USD
CY2020	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	329000	USD
CY2018	us-gaap	Current State And Local Tax Expense Benefit CurrentStateAndLocalTaxExpenseBenefit	298000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	21958000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	23224000	USD
CY2018	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	21628000	USD
CY2020	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	-5070000	USD
CY2019	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	2284000	USD
CY2018	us-gaap	Deferred Federal Income Tax Expense Benefit DeferredFederalIncomeTaxExpenseBenefit	3666000	USD
CY2020	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-132000	USD
CY2019	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	8000	USD
CY2018	us-gaap	Deferred State And Local Income Tax Expense Benefit DeferredStateAndLocalIncomeTaxExpenseBenefit	-20000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-5202000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	2292000	USD
CY2018	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	3646000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16756000	USD
CY2019	fcf	Income Tax Reconciliation Bank Owned Life Insurance Income IncomeTaxReconciliationBankOwnedLifeInsuranceIncome	1260000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25516000	USD
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25274000	USD
CY2020	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	18943000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2019	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	27478000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2018	us-gaap	Income Tax Reconciliation Income Tax Expense Benefit At Federal Statutory Income Tax Rate IncomeTaxReconciliationIncomeTaxExpenseBenefitAtFederalStatutoryIncomeTaxRate	27882000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2020	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	155000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0
CY2019	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	229000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0
CY2018	us-gaap	Income Tax Reconciliation State And Local Income Taxes IncomeTaxReconciliationStateAndLocalIncomeTaxes	220000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0
CY2020	fcf	Income Tax Reconciliation Bank Owned Life Insurance Income IncomeTaxReconciliationBankOwnedLifeInsuranceIncome	1376000	USD
CY2020	fcf	Effective Income Tax Rate Reconciliation Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationBankOwnedLifeInsurance	0.01
CY2019	fcf	Effective Income Tax Rate Reconciliation Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationBankOwnedLifeInsurance	0.01
CY2018	fcf	Income Tax Reconciliation Bank Owned Life Insurance Income IncomeTaxReconciliationBankOwnedLifeInsuranceIncome	1404000	USD
CY2018	fcf	Effective Income Tax Rate Reconciliation Bank Owned Life Insurance EffectiveIncomeTaxRateReconciliationBankOwnedLifeInsurance	0.01
CY2020	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	1117000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.01
CY2019	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	1298000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.01
CY2018	us-gaap	Income Tax Reconciliation Tax Exempt Income IncomeTaxReconciliationTaxExemptIncome	1473000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Exempt Income EffectiveIncomeTaxRateReconciliationTaxExemptIncome	0.01
CY2020	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	44000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2019	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	7000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2018	us-gaap	Income Tax Reconciliation Tax Credits IncomeTaxReconciliationTaxCredits	5000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Tax Credits EffectiveIncomeTaxRateReconciliationTaxCredits	0
CY2020	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2019	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	0	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2018	us-gaap	Income Tax Reconciliation Change In Enacted Tax Rate IncomeTaxReconciliationChangeInEnactedTaxRate	-346000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Change In Enacted Tax Rate EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate	0
CY2020	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	195000	USD
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2019	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	374000	USD
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2018	us-gaap	Income Tax Reconciliation Other Adjustments IncomeTaxReconciliationOtherAdjustments	400000	USD
CY2018	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16756000	USD
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.19
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25516000	USD
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.19
CY2018	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	25274000	USD
CY2018	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.19
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.21
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.19
CY2020Q4	fcf	Deferred Tax Asset Tax Deferred Expense Lease Liability DeferredTaxAssetTaxDeferredExpenseLeaseLiability	9928000	USD
CY2019Q4	fcf	Deferred Tax Asset Tax Deferred Expense Lease Liability DeferredTaxAssetTaxDeferredExpenseLeaseLiability	11203000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	21483000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Provision For Loan Losses DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsProvisionForLoanLosses	10937000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	242000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Postretirement Benefits DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits	275000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Alternative Minimum Tax DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax	0	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Credit Carryforwards Alternative Minimum Tax DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax	216000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	385000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	2017000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	1723000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Pensions DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPensions	1720000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	644000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Accrued Liabilities DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities	710000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	2182000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Other DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsOther	2185000	USD
CY2020Q4	fcf	Deferred Tax Assets Unfunded Loan Commitment Allowance DeferredTaxAssetsUnfundedLoanCommitmentAllowance	1576000	USD
CY2019Q4	fcf	Deferred Tax Assets Unfunded Loan Commitment Allowance DeferredTaxAssetsUnfundedLoanCommitmentAllowance	964000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1831000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1032000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	39994000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	31259000	USD
CY2020Q4	fcf	Deferred Tax Liabilities Loan Origination Fees And Costs DeferredTaxLiabilitiesLoanOriginationFeesAndCosts	1280000	USD
CY2019Q4	fcf	Deferred Tax Liabilities Loan Origination Fees And Costs DeferredTaxLiabilitiesLoanOriginationFeesAndCosts	626000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	9037000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Leasing Arrangements DeferredTaxLiabilitiesLeasingArrangements	10302000	USD
CY2020Q4	fcf	Net Unrealized Gain On Investment Securities Available For Sale NetUnrealizedGainOnInvestmentSecuritiesAvailableForSale	4629000	USD
CY2019Q4	fcf	Net Unrealized Gain On Investment Securities Available For Sale NetUnrealizedGainOnInvestmentSecuritiesAvailableForSale	1386000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	2103000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Property Plant And Equipment DeferredTaxLiabilitiesPropertyPlantAndEquipment	1470000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	540000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Goodwill And Intangible Assets Intangible Assets DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets	45000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	424000	USD
CY2019Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	568000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	18013000	USD
CY2019Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	14397000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	21981000	USD
CY2019Q4	us-gaap	Deferred Tax Assets Liabilities Net DeferredTaxAssetsLiabilitiesNet	16862000	USD
CY2020Q4	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	1500000	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2020	fcf	Percentage Of Employees Eligible Compensation That Represents Maximum Amount Of Employer Matching Contributions To Four Zero One K Plan PercentageOfEmployeesEligibleCompensationThatRepresentsMaximumAmountOfEmployerMatchingContributionsToFourZeroOneKPlan	0.06
CY2020	us-gaap	Defined Contribution Plan Maximum Annual Contributions Per Employee Percent DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent	0.80
CY2020	fcf	Deferred Compensation Plan Net Of Contribution Expenses DeferredCompensationPlanNetOfContributionExpenses	3900000	USD
CY2019	fcf	Deferred Compensation Plan Net Of Contribution Expenses DeferredCompensationPlanNetOfContributionExpenses	3600000	USD
CY2018	fcf	Deferred Compensation Plan Net Of Contribution Expenses DeferredCompensationPlanNetOfContributionExpenses	3200000	USD
CY2020	fcf	Retirement Plan Expense RetirementPlanExpense	0	USD
CY2020	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	0	USD
CY2018	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	38000	USD
CY2019	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	0	USD
CY2018	us-gaap	Defined Benefit Plan Service Cost DefinedBenefitPlanServiceCost	0	USD
CY2020	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	23000	USD
CY2019	us-gaap	Defined Benefit Plan Interest Cost DefinedBenefitPlanInterestCost	34000	USD
CY2020	us-gaap	Defined Benefit Plan Amortization Of Transition Asset Obligation DefinedBenefitPlanAmortizationOfTransitionAssetObligation	0	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Transition Asset Obligation DefinedBenefitPlanAmortizationOfTransitionAssetObligation	0	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Transition Asset Obligation DefinedBenefitPlanAmortizationOfTransitionAssetObligation	0	USD
CY2020	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	52000	USD
CY2019	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	60000	USD
CY2018	us-gaap	Defined Benefit Plan Amortization Of Gains Losses DefinedBenefitPlanAmortizationOfGainsLosses	35000	USD
CY2020	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	-29000	USD
CY2019	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	-26000	USD
CY2018	us-gaap	Defined Benefit Plan Net Periodic Benefit Cost DefinedBenefitPlanNetPeriodicBenefitCost	3000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	1372000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Funded Status Of Plan DefinedBenefitPlanFundedStatusOfPlan	834000	USD
CY2020	fcf	Defined Benefit Plan Unrecognized Net Transition Obligation DefinedBenefitPlanUnrecognizedNetTransitionObligation	537000	USD
CY2019	fcf	Defined Benefit Plan Unrecognized Net Transition Obligation DefinedBenefitPlanUnrecognizedNetTransitionObligation	0	USD
CY2020	fcf	Defined Benefit Plan Unrecognized Net Actuarial Gains Losses DefinedBenefitPlanUnrecognizedNetActuarialGainsLosses	308000	USD
CY2019	fcf	Defined Benefit Plan Unrecognized Net Actuarial Gains Losses DefinedBenefitPlanUnrecognizedNetActuarialGainsLosses	463000	USD
CY2020	fcf	Defined Benefit Plan Recognized In Retained Earnings DefinedBenefitPlanRecognizedInRetainedEarnings	1143000	USD
CY2019	fcf	Defined Benefit Plan Recognized In Retained Earnings DefinedBenefitPlanRecognizedInRetainedEarnings	1297000	USD
CY2020Q4	us-gaap	Defined Benefit Pension Plan Current And Noncurrent Liabilities DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities	1372000	USD
CY2019Q4	us-gaap	Defined Benefit Pension Plan Current And Noncurrent Liabilities DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities	834000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains Losses Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax	243000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains Losses Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax	366000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Gains Losses Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax	461000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Transition Assets Obligations Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetTransitionAssetsObligationsBeforeTax	-424000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Transition Assets Obligations Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetTransitionAssetsObligationsBeforeTax	0	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Net Transition Assets Obligations Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetTransitionAssetsObligationsBeforeTax	0	USD
CY2020Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax	181000	USD
CY2019Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax	-366000	USD
CY2018Q4	us-gaap	Defined Benefit Plan Accumulated Other Comprehensive Income Before Tax DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeBeforeTax	-461000	USD
CY2020	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Service And Interest Cost Components DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnServiceAndInterestCostComponents	30000	USD
CY2020	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Service And Interest Cost Components1 DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnServiceAndInterestCostComponents1	29000	USD
CY2020	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Increase On Accumulated Postretirement Benefit Obligation DefinedBenefitPlanEffectOfOnePercentagePointIncreaseOnAccumulatedPostretirementBenefitObligation	1000	USD
CY2020	us-gaap	Defined Benefit Plan Effect Of One Percentage Point Decrease On Accumulated Postretirement Benefit Obligation1 DefinedBenefitPlanEffectOfOnePercentagePointDecreaseOnAccumulatedPostretirementBenefitObligation1	0	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Next Twelve Months DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths	165000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Two DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo	157000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Three DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree	147000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Four DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour	136000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Year Five DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive	124000	USD
CY2020Q4	us-gaap	Defined Benefit Plan Expected Future Benefit Payments Five Fiscal Years Thereafter DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter	455000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized	5000000	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant	2689027	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	9.37
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	117000	shares
CY2017Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	9.99
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	95300	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	171500	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	14.27
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	137500	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	13.05
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	13.72
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	78000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	14.22
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod	84500	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	14.50
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	12000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	0
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	41000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue	10.09
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod	54000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	4000	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	13.85
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	3000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	14.40
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeited In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod	10000	shares
CY2018	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Forfeitures Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue	9.34
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	250800	shares
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	14.13
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	171500	shares
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	14.27
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber	137500	shares
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue	13.05
CY2015Q4	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P5Y
CY2015Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2016Q1	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P3Y
CY2016Q1	fcf	Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfTargetAwardParticipantsEarn	0.40
CY2016Q1	fcf	Performance Shares Awards As Percentage Of Target PerformanceSharesAwardsAsPercentageOfTarget	1
CY2016Q1	fcf	Percentage Of Target Award Opportunities Maximum In Certain Cases PercentageOfTargetAwardOpportunitiesMaximumInCertainCases	2
CY2016Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2017Q1	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P3Y
CY2017Q1	fcf	Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfTargetAwardParticipantsEarn	0.40
CY2017Q1	fcf	Performance Shares Awards As Percentage Of Target PerformanceSharesAwardsAsPercentageOfTarget	1
CY2017Q1	fcf	Percentage Of Target Award Opportunities Maximum In Certain Cases PercentageOfTargetAwardOpportunitiesMaximumInCertainCases	2
CY2017Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2018Q1	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P3Y
CY2018Q1	fcf	Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfTargetAwardParticipantsEarn	0.40
CY2018Q1	fcf	Performance Shares Awards As Percentage Of Target PerformanceSharesAwardsAsPercentageOfTarget	1
CY2018Q1	fcf	Percentage Of Target Award Opportunities Maximum In Certain Cases PercentageOfTargetAwardOpportunitiesMaximumInCertainCases	2
CY2018Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2019Q1	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P3Y
CY2019Q1	fcf	Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfTargetAwardParticipantsEarn	0.40
CY2019Q1	fcf	Performance Shares Awards As Percentage Of Target PerformanceSharesAwardsAsPercentageOfTarget	1
CY2019Q1	fcf	Percentage Of Target Award Opportunities Maximum In Certain Cases PercentageOfTargetAwardOpportunitiesMaximumInCertainCases	2
CY2019Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2020Q1	fcf	Performance Based Stock Awards Vesting Period PerformanceBasedStockAwardsVestingPeriod	P3Y
CY2020Q1	fcf	Share Based Compensation Arrangement By Share Based Payment Award Percentage Of Target Award Participants Earn ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfTargetAwardParticipantsEarn	0.40
CY2020Q1	fcf	Performance Shares Awards As Percentage Of Target PerformanceSharesAwardsAsPercentageOfTarget	1
CY2020Q1	fcf	Percentage Of Target Award Opportunities Maximum In Certain Cases PercentageOfTargetAwardOpportunitiesMaximumInCertainCases	2
CY2020Q1	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P0Y
CY2020	fcf	Incentive Revenue IncentiveRevenue	500000	USD
CY2020	us-gaap	Brokerage Commissions Revenue BrokerageCommissionsRevenue	3000000.0	USD
CY2020	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	9101000	USD
CY2019	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	8321000	USD
CY2018	fcf	Feesand Commissionson Trustand Fiduciary Accounts FeesandCommissionsonTrustandFiduciaryAccounts	7901000	USD
CY2020	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	16387000	USD
CY2019	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	18926000	USD
CY2018	fcf	Feesand Commissionson Depositor Accounts FeesandCommissionsonDepositorAccounts	18175000	USD
CY2020	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7850000	USD
CY2019	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7583000	USD
CY2018	us-gaap	Insurance Commissions And Fees InsuranceCommissionsAndFees	7426000	USD
CY2020	fcf	Feesand Commissionson Debit Cards FeesandCommissionsonDebitCards	23966000	USD
CY2019	fcf	Feesand Commissionson Debit Cards FeesandCommissionsonDebitCards	21677000	USD
CY2018	fcf	Feesand Commissionson Debit Cards FeesandCommissionsonDebitCards	20187000	USD
CY2020	us-gaap	Noninterest Income NoninterestIncome	94476000	USD
CY2019	us-gaap	Noninterest Income NoninterestIncome	85485000	USD
CY2018	us-gaap	Noninterest Income NoninterestIncome	88637000	USD
CY2019Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	19246000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Additions LoansAndLeasesReceivableRelatedPartiesAdditions	4258000	USD
CY2020	us-gaap	Loans And Leases Receivable Related Parties Proceeds LoansAndLeasesReceivableRelatedPartiesProceeds	3931000	USD
CY2020Q4	us-gaap	Loans And Leases Receivable Related Parties LoansAndLeasesReceivableRelatedParties	19573000	USD
CY2018Q2	us-gaap	Subordinated Long Term Debt SubordinatedLongTermDebt	100000000	USD
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1100000000	USD
CY2020	us-gaap	Stockholders Equity Period Increase Decrease StockholdersEquityPeriodIncreaseDecrease	13000000.0	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73400000	USD
CY2020	fcf	Proceeds From Reissuance Of Common Stock ProceedsFromReissuanceOfCommonStock	1800000	USD
CY2020	fcf	Increase Decrease In Fair Value Of Debt Securities Available For Sale IncreaseDecreaseInFairValueOfDebtSecuritiesAvailableForSale	11700000	USD
CY2020	us-gaap	Payments Of Dividends PaymentsOfDividends	43000000.0	USD
CY2020	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	20900000	USD
CY2020Q4	us-gaap	Cumulative Effect Of New Accounting Principle In Period Of Adoption CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	11200000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.44
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.40
CY2018Q4	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000.0	USD
CY2019	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	1843373	shares
CY2019	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	13.58
CY2019Q1	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	25000000.0	USD
CY2020	us-gaap	Stock Repurchased During Period Shares StockRepurchasedDuringPeriodShares	2761504	shares
CY2020	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	9.07
CY2020	us-gaap	Net Income Loss NetIncomeLoss	73447000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	105333000	USD
CY2018	us-gaap	Net Income Loss NetIncomeLoss	107498000	USD
CY2020	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.44
CY2019	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.40
CY2018	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.35
CY2020	fcf	Commitment On Line Of Credit CommitmentOnLineOfCredit	20000000.0	USD

Files In Submission

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$FCF
FIRST COMMONWEALTH FINANCIAL CORP /PA/ Stock $fcf

2020 Form 10-K Financial Statement

#000071253721000007 Filed on March 01, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FCF FIRST COMMONWEALTH FINANCIAL CORP /PA/ Stock $fcf

2020 Form 10-K Financial Statement

#000071253721000007 Filed on March 01, 2021

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$FCF
FIRST COMMONWEALTH FINANCIAL CORP /PA/ Stock $fcf