Document And Entity Information Securities available for sale, due after ten years, fair value Expected dividend yield Note To Financial Statement Details Textual Derivative expense Significant Accounting Policies us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis Securities available for sale, single maturity date, amortized cost Note 2 - Acquisitions and Divestitures Securities available for sale, due within one year, amortized cost Note 3 - Debt Securities us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate Securities available for sale, single maturity date, fair value Risk-free rate Note 4 - Loans Securities available for sale, due within one year, fair value Note 5 - Credit Quality Securities available for sale, due after one year but within five years, fair value Note 6 - Allowance for Loan Losses Securities available for sale, due after five years but within ten years, fair value Note 7 - FDIC Indemnification Asset Collateralized Mortgage Backed Securities [Member] Volatility Note 8 - Premises, Equipment, and Leases Note 9 - Goodwill and Other Intangible Assets Note 10 - Deposits Note 11 - Borrowings Note 12 - Derivative Instruments and Hedging Activities Note 13 - Employee Benefit Plans Note 14 - Other Operating Income and Expense Note 15 - Income Taxes Note 16 - Accumulated Other Comprehensive Income Note 17 - Fair Value Note 18 - Earnings Per Share Expected term (Year) Note 19 - Related Party Transactions Note 20 - Litigation, Commitments, and Contingencies Note 21 - Regulatory Requirements and Restrictions Note 22 - Parent Company Financial Information Note 23 - Quarterly Financial Data (Unaudited) US States and Political Subdivisions Debt Securities [Member] Note 2 - Acquisitions and Divestitures - Net Cash (Received) Paid in Acquisitions and Divestitures (Details) Note 3 - Debt Securities - Securities Available-for-sale (Details) Note 3 - Debt Securities - Securities by Contractual Maturity (Details) Note 3 - Debt Securities - Securities Held to Maturity (Details) Note 3 - Debt Securities - Amortized Cost and Fair Value of Municipal Securities by State, Including Gross Unrealized Gains and Losses (Details) Note 3 - Debt Securities - Available For Sale Securities in Continuous Unrealized Loss Position (Details) Note 3 - Debt Securities - Held to Maturity Securities in Continuous Unrealized Loss Position (Details) Note 3 - Debt Securities - Credit Losses Recognized in Earnings for Debt Securities Where Portion of Impairment Recognized in OCI (Details) Granted (in dollars per share) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue Note 3 - Debt Securities - Gross Realized Gains and Losses from Sale of Available-for-sale Debt Securities (Details) Vested (in dollars per share) Canceled (in dollars per share) Note 4 - Loans - Loans by Class (Details) US Treasury Securities [Member] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue Nonvested shares at beginning of period (in dollars per share) Nonvested shares at end of period (in dollars per share) Note 4 - Loans - Covered Loans by Class (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod Canceled (in shares) Note 4 - Loans - PCI loans (Details) Note 4 - Loans - Activity in Accretable Yield on PCI loans (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber Nonvested shares at beginning of period (in shares) Nonvested shares at end of period (in shares) Note 5 - Credit Quality - Loans by Credit Quality (Details) Note 5 - Credit Quality - Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) Schedule of Derivative Instruments [Table Text Block] Other comprehensive income (loss) before reclassifications Note 5 - Credit Quality - Average Annual Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) US Government Agencies Debt Securities [Member] us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent Reclassified from AOCI Note 5 - Credit Quality - Information on Impaired PCI Loan Pools (Details) Note 5 - Credit Quality - Nonaccrual Loans by Loan Class (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod Granted (in shares) Corporate Debt Securities [Member] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod Vested (in shares) Note 5 - Credit Quality - Aging of Past Due Loans by Loan Class (Details) Note 5 - Credit Quality - Loans Modified as Troubled Debt Restructurings by Loan Class and Accrual Status (Details) Note 5 - Credit Quality - Balance and Interest Income Related to Impaired Loan Pools (Details) Note 5 - Credit Quality - Loans Modified as Troubled Debt Restructurings (Details) Note 5 - Credit Quality - Other Real Estate Owned (Details) Options exercisable at end of period Note 6 - Allowance for Loan Losses - Changes in Allowance for Loan Losses (Details) Note 6 - Allowance for Loan Losses - Allowance for Loan Losses and Recorded Investment in Loans, Evaluated for Impairment Excluding PCI Loans, by Loan Class (Details) Note 6 - Allowance for Loan Losses - Allowance for Loan Losses on PCI Loans and Recorded Investment (Details) Note 7 - FDIC Indemnification Asset - Changes in Receivable From FDIC (Details) Options outstanding at end of period Note 8 - Premises, Equipment, and Leases - Components of Premises and Equipment (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice Options exercisable at end of period (in dollars per share) Note 8 - Premises, Equipment, and Leases - Future Minimum Lease Payments to be Received Under Noncancelable Subleases (Details) Options exercisable at end of period (Year) Note 9 - Goodwill and Other Intangible Assets - Changes in Goodwill, by Reporting Unit (Details) Note 9 - Goodwill and Other Intangible Assets - Components of Other Intangible Assets, by Reporting Unit (Details) us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax Income before income taxes Note 9 - Goodwill and Other Intangible Assets - Estimated Amortization Expense for Intangible Assets, by Year (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value Note 10 - Deposits - Components of Deposits (Details) Note 10 - Deposits - Scheduled Maturities of Time Deposits (Details) us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax Net income Note 10 - Deposits - Scheduled Maturities of Certificates of Deposit of $250 Thousand or More (Details) Options exercisable at end of period (in shares) Note 11 - Borrowings - Components of Borrowings (Details) Note 11 - Borrowings - Contractual Maturities of Repurchase Agreements (Details) Options outstanding at end of period (Year) Note 12 - Derivative Instruments and Hedging Activities - Notional or Contractual Amounts and Fair Values of Derivative Financial Instruments (Details) Note 12 - Derivative Instruments and Hedging Activities - Effect of Derivative and Hedging Activity, on Consolidated Statements of Income (Details) Grant-date fair value per share (in dollars per share) Note 13 - Employee Benefit Plans - Schedule of Changes in Aggregate Actuarial Benefit Obligation (Details) Note 13 - Employee Benefit Plans - Components of Net Periodic Pension Cost and Assumed Discount Rate (Details) Note 13 - Employee Benefit Plans - Projected Benefit Payments (Details) Note 13 - Employee Benefit Plans - Pre-tax Compensation Expense and Excess Tax Benefit Recognized in Earnings (Details) Note 13 - Employee Benefit Plans - Stock Option Activity (Details) Note 13 - Employee Benefit Plans - Total Options Granted and Weighted Average Assumptions Used to Estimate Fair Value (Details) Note 13 - Employee Benefit Plans - Restricted Stock Activity (Details) Note 14 - Other Operating Income and Expense - Components of Other Operating Income and Expense (Details) Financial Instruments [Domain] Note 15 - Income Taxes - Components of Income Tax Provision (Details) us-gaap_LoansAndLeasesReceivableRelatedPartiesProceeds Loan repayments Note 15 - Income Taxes - Reconciliation of Statutory Federal Tax Rate and Effective Tax Rate From Continuing Operations (Details) Note 15 - Income Taxes - Significant Components of Net Deferred Tax Asset (Details) us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice Options outstanding at beginning of period (in dollars per share) Options outstanding at end of period (in dollars per share) Note 16 - Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) Property Subject to or Available for Operating Lease [Axis] Note 16 - Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Details) Property Subject to or Available for Operating Lease [Domain] us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice Canceled (in dollars per share) Note 17 - Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) Note 17 - Fair Value - Changes in Level 3 Fair Value Measurements (Details) Financial Instrument [Axis] New loans and advances Note 17 - Fair Value - Assets Measured at Fair Value on Nonrecurring Basis (Details) Note 17 - Fair Value - Quantitative Information for Assets Measured at Fair Value on Nonrecurring Basis (Details) Note 17 - Fair Value - Financial Instruments (Details) Note 18 - Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details) us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice Granted (in dollars per share) Securities available for sale, no single maturity date, fair value Note 19 - Related Party Transactions - Changes in Loans With Related Parties (Details) us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice Exercised (in dollars per share) Note 20 - Litigation, Commitments, and Contingencies - Off-balance Sheet Financial Instruments (Details) Note 21 - Regulatory Requirements and Restrictions - Company's and Bank's Capital Ratios (Details) Note 22 - Parent Company Financial Information - Condensed Balance Sheets (Details) Note 22 - Parent Company Financial Information - Condensed Statements of Income (Details) Note 22 - Parent Company Financial Information - Condensed Statements of Cash Flows (Details) Provision (Recovery) for loan losses Amount of (recovery of) provision for loans and lease receivables which had previously been fully or partially written-off as bad debts. Note 23 - Quarterly Financial Data (Unaudited) - Summary of Quarterly Earnings (Details) Securities available for sale, no single maturity date, amortized cost Allowance Excluding Purchased Credit Impaired Loans [Member] Information pertaining to the allowance excluding purchased credit impaired loans. Notes To Financial Statements Fair value maturity: Notes To Financial Statements [Abstract] Recovery of loan losses recorded through the FDIC indemnification asset Amount of expense (recovery) related to estimated loss from loan and lease transactions recorded through FDIC indemnification asset. us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber Options outstanding at beginning of period (in shares) Options outstanding at end of period (in shares) Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Benefit attributable to the FDIC indemnification asset Represents the amount of provision (benefit) for loan losses. Amortized cost maturity: Allowance for Credit Losses and Recorded Investment in Loans by Segment and Class [Table Text Block] Tabular disclosure of allowance for credit losses and recorded investment in loans by segment and class. us-gaap_PolicyTextBlockAbstract Accounting Policies Gross realized gains us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield Beginning balance Ending balance us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss Gross realized losses Reclassifications from nonaccretable difference(1) Schedule of Information Related to Purchased Credit Impaired Loans [Table Text Block] Tabular disclosure of information related to purchased credit impaired loans. us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion Accretion Waccamaw Commercial [Member] Information pertaining to Waccamaw Commercial loans. Waccamaw Serviced Home Equity Lines [Member] Information pertaining to Waccamaw serviced home equity lines. PCI loans, unpaid principal balance Allowance for Credit Losses [Text Block] Waccamaw Residential [Member] Information pertaining to Waccamaw residential loans. PCI loans, recorded investment Peoples Commercial [Member] Information pertaining to Peoples Commercial loans. Other Commercial Loan [Member] Information pertaining to other commercial loans. us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Allowance for acquired impaired loans Represents the amount of allowance for acquired impaired loans. FDIC Loss Share Agreement Receivable [Text Block] Entire disclosure of FDIC loss share agreement. Peoples Residential [Member] Information pertaining to Peoples residential loans. us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage Acquired impaired loans evaluated for impairment Represents the amount of acquired impaired loans evaluated for impairment. Liabilities fcbc_PercentageOfLossCoveredByFDIC Percentage of Loss Covered by FDIC Represents the percentage of loss covered by the FDIC. Reimbursable expenses (to) from the FDIC Amount of increases to the indemnification asset due to acquisitions of assets relating reimbursable expenses accrued with the Federal Deposit Insurance Corporation (FDIC). Vesting [Axis] Vesting [Domain] Share-based Compensation Award, Tranche One [Member] Total assets Total assets us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation Disposal Group, Including Discontinued Operation, Assets, Total Below Market Interest Rate and Extended Payment Term [Member] Information pertaining to below market interest rates and extended payment terms. Unsecured Line of Credit [Member] Information pertaining to the unsecured line of credit. Plan Name [Axis] Plan Name [Domain] Below Market Interest Rate [Member] Information pertaining to below market interest rates. Compensation and Employee Benefit Plans [Text Block] us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options Wholesale Repurchase Agreements [Member] Information pertaining to wholesale repurchase agreements. us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1 Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Long-term Advances [Member] Information pertaining to long-term advances. Retail Repurchase Agreements [Member] Information pertaining to retail repurchase agreements. Weighted average rate fcbc_WeightedAverageContractualRate Represents the weighted average contractual rate. us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net Maturity Overnight and Continuous [Member] Maturity period of the day after the reporting date and continuous for repurchase agreements and similar transactions, for example, but not limited to, securities lending arrangements. Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block] Other assets Equity Award [Domain] Award Type [Axis] us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization Accumulated amortization us-gaap_FiniteLivedIntangibleAssetsNet Total estimated amortization expense Finite-lived intangible assets, net Other intangible assets Interest and Fees on Loans [Member] Primary financial statement caption encompassing interest and fees on loans. Directors' Plan [Member] Information pertaining to the Directors' Supplemental Retirement Plan (the Directors' Plan"). Finite-lived intangible assets, gross Deferred compensation liabilities Fair value portion of deferred compensation liabilities. Deferred compensation assets Deferred compensation assets Fair value portion of deferred compensation assets. Commitments and Contingencies Disclosure [Text Block] us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Accumulated depreciation and amortization Impaired Loans [Member] Information pertaining to impaired loans. Premises and equipment, net Total premises and equipment, net Goodwill Balance Balance Bank Time Deposits [Member] OREO [Member] Information pertaining to other real estate owned (OREO). us-gaap_PropertyPlantAndEquipmentGross Total premises and equipment Savings Deposits [Member] Information pertaining to savings deposits. Land Buildings and leasehold improvements Greenpoint Insurance Group [Member] Information pertaining to Greenpoint Insurance Group. Equipment Reserve for unfunded commitments Represents the amount of reserve for unfunded credit commitments. Virginia [Member] Information pertaining to Virginia. Allowance for loan losses related to TDRs Represents the amount of allowance for loan losses. us-gaap_OtherPostretirementBenefitExpense Other Postretirement Benefits Cost (Reversal of Cost) Derivative financial assets Derivative assets Derivative Instrument [Axis] Derivative Contract [Domain] us-gaap_EquitySecuritiesWithoutReadilyDeterminableFairValueAmount Equity Securities without Readily Determinable Fair Value, Amount Available-for-sale debt securities Debt securities available for sale Securities available for sale Debt securities held to maturity Total amortized cost Securities held to maturity, amortized cost Investment in subsidiaries us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings, Total Income before income taxes and equity in undistributed net income of subsidiaries Income tax expense Total income tax expense Income tax expense us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest Portion of loss recognized in other comprehensive income Residential real estate loans in the foreclosure process(1) us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld Beginning balance Ending balance Additions for credit losses on securities previously recognized us-gaap_OtherExpenses Other(1) Unrealized gains on available-for-sale securities Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on available-for-sale securities. Additions for credit losses on securities not previously recognized us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold Reduction for securities sold/realized losses After five years through ten years, amortized cost After ten years, amortized cost Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table Text Block] Held-to-maturity, Amortized cost maturity: Reclassification from AOCI to Retained Earnings [Member] Represent information about reclassification from AOCI to retained earnings. us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent One year or less, amortized cost After one year through five years, amortized cost Twelve Months Ended December 31, 2017 [Member] Represents information about period of twelve months ended December 31, 2017. One year or less Interest-bearing deposits in banks After one year through five years After five years through ten years After ten years us-gaap_CashAndCashEquivalentsAtCarryingValue Total cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss Securities held to maturity, unrealized losses Securities held to maturity, unrealized gains Salaries and employee benefits Increase in estimated losses on covered OREO Cash and due from banks Telephone and data communications us-gaap_DefinedBenefitPlanBenefitObligation Beginning balance Ending balance us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter 2024 through 2028 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo 2020 Community Banking [Member] Represents the community banking reporting unit. us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree 2021 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour 2022 Acquisitions and dispositions, net Represents the net of goodwill acquired and disposed of during period. us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive 2023 Other (1) Amount of goodwill translation adjustments and other goodwill items not individually specified. Amendment Flag Scheduled Maturities of Certificates of Deposits, Greater than 250,000 [Table Text Block] Tabular disclosure of time deposit liabilities of 250,000 or more. Three months or less Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within three months or fewer from the balance sheet date. FDIC Indemnification Asset Roll Forward [Table Text Block] us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths 2019 Use of Estimates, Policy [Policy Text Block] Net gain on divestitures Gain (Loss) on Disposition of Business Gain on divestiture, net Over twelve months Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing after twelve months from the balance sheet date. New Accounting Pronouncements, Policy [Policy Text Block] fcbc_DefinedBenefitPlanEmployeeContributionAge Defined Benefit Plan, Employee Contribution, Age Represents the employee contribution age for defined benefit plan. Over three through six months Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within three to six months after the balance sheet date. Over six through twelve months Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within six to twelve months after the balance sheet date. Reclassification, Policy [Policy Text Block] fcbc_DefinedContributionPlanMaximumEmployeeContributionAsPercentageOfBaseSalary Defined Contribution Plan, Maximum Employee Contribution as Percentage of Base Salary Represents the maximum percentage of base salary the employee contribution. us-gaap_PriorPeriodReclassificationAdjustment Prior Period Reclassification Adjustment us-gaap_GainLossOnSaleOfPropertyPlantEquipment (Gain) loss on sale of premises and equipment, net fcbc_StoplossInsuranceLiabilityForAggregateClaims Stop-loss Insurance Liability for Aggregate Claims Amount of stop-loss insurance coverage for aggregate claims. fcbc_StoplossInsuranceLiabilityForIndividualClaims Stop-loss Insurance Liability for Individual Claims Amount of stop-loss insurance coverage for individual claims. Securities held to maturity, total fair value fcbc_DefinedBenefitPlanEmployerMatchingContributions Defined Benefit Plan, Employer Matching Contributions Amount of employer matching contributions to the plan. Current Fiscal Year End Date fcbc_SharebasedCompensationArrangementBySharebasedPaymentAwardMaximumExercisePeriod Share-based Compensation Arrangement By Share-based Payment Award, Maximum Exercise Period Period from grant date that an equity-based award can be exercised, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Securities held to maturity, less than 12 months fair value 401 (k) Savings Plan [Member] Represents the company's 401K savings plan. Assumed discount rate Securities held to maturity, 12 months or longer fair value Basis of Accounting [Text Block] us-gaap_DebtSecuritiesAvailableForSaleRealizedGainLoss Loss (gain) on sale of securities Net (loss) gain on sale of securities Interest receivable Document Fiscal Period Focus 2012 Omnibus Incentive Compensation Plan [Member] Represents the 2012 Omnibus Incentive compensation plan. Document Fiscal Year Focus Consolidation, Policy [Policy Text Block] Document Period End Date Tier 1 Leverage, actual ratio Tier 1 Leverage, required ratio Entity Emerging Growth Company Entity Shell Company Tier 1 Leverage, to be well capitalized ratio Document Type us-gaap_InvestmentOwnedAtCost Investment Owned, at Cost Total risk-based capital, to be well capitalized ratio Entity Small Business Common equity Tier 1, actual ratio Goodwill impairment Document Information [Line Items] Document Information [Table] Total risk-based capital, actual ratio Total risk-based capital, required ratio Entity Public Float us-gaap_DefinedBenefitPlanBenefitObligationBenefitsPaid Benefits paid Entity Filer Category Tier 1 risk-based capital, actual ratio Entity Current Reporting Status Tier 1 risk-based capital, required ratio Entity Voluntary Filers us-gaap_BusinessCombinationAcquisitionRelatedCosts Business Combination, Acquisition Related Costs Tier 1 risk-based capital, to be well capitalized ratio Entity Well-known Seasoned Issuer Total risk-based capital ratio, actual amount fcbc_PercentageOfOperatingIncome Percentage of Operating Income Represents the percentage of operating income that other components cannot exceed. Plan change Total risk-based capital ratio, required amount us-gaap_DefinedBenefitPlanActuarialGainLoss Actuarial gain Total risk-based capital to be well capitalized, amount Held-to-maturity, Fair value maturity: fcbc_OtherMiscellaneousIncome Other(1) Amounts of all other miscellaneous income not separately disclosed. us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Securities held to maturity, 12 months or longer unrealized losses Tier 1 Leverage ratio, actual amount us-gaap_GoodwillImpairmentLoss Goodwill, Impairment Loss Impairment charges fcbc_IncomeTaxReconciliationFederalStateAndLocalIncomeTaxes Total effective income tax rate reconciliation, amount Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to domestic, state, and local income tax expense. Tier 1 Leverage ratio, required amount Tier 1 Leverage to be well capitalized, amount us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Securities held to maturity, less than 12 months unrealized losses Debt Securities, Held-to-maturity [Table Text Block] Common equity Tier 1 ratio, actual amount Statement of Comprehensive Income [Abstract] Common equity Tier 1 ratio, required amount us-gaap_ImpairmentOfLongLivedAssetsToBeDisposedOf Impairment of Long-Lived Assets to be Disposed of Common equity Tier 1 to be well capitalized, amount Entity Central Index Key Tier 1 risk-based capital ratio, actual amount Entity Registrant Name Tier 1 risk-based capital ratio, required amount fcbc_EffectiveIncomeTaxRateReconciliationFederalStateAndLocalIncomeTaxes Total effective income tax rate reconciliation Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to domestic, state, and local income taxes. Tier 1 risk-based capital to be well capitalized, amount Entity [Domain] Legal Entity [Axis] Amortization of intangible assets Amortization of intangibles Amortization of Intangible Assets, Total Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] FDIC indemnification asset Beginning balance Ending balance Regulatory Capital Requirements under Banking Regulations [Text Block] Other real estate owned (includes covered OREO of $32 and $105, respectively) Total OREO Covered OREO Other real estate owned, covered us-gaap_OtherRevenueExpenseFromRealEstateOperations OREO expense and net loss Non-covered OREO us-gaap_OtherRealEstateNonCovered Entity Common Stock, Shares Outstanding (in shares) Depreciation and amortization of premises and equipment Depreciation, Nonproduction FDIC assisted transactions Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from Federal Deposit Insurance Company (FDIC) transactions. fcbc_DeferredTaxLiabilitiesFederalDepositInsuranceCompanyTransaction FDIC indemnification asset Amount of deferred tax liability attributable to taxable temporary differences from Federal Deposit Insurance Company (FDIC) transactions. Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Purchase accounting Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from purchase accounting. Advertising and public relations us-gaap_LoansAndLeasesReceivableNetReportedAmountCoveredAndNotCovered Loans held for investment, net Professional fees Non-covered loans Non-covered us-gaap_LoansAndLeasesReceivableAllowance Loans and Leases Receivable, Allowance, Ending Balance Allowance for loan losses Beginning balance Ending balance Investments [Domain] Trading Symbol Office supplies Occupancy expense Investment Type [Axis] fcbc_CapitalConservationBuffer Capital Conservation Buffer An additional amount held in risk-based capital designed to ensure that banks build up capital buffers outside periods of stress which can be drawn down as losses are incurred. The requirement is based on simple capital conservation rules designed to avoid breaches of minimum capital requirements. us-gaap_TableTextBlock Notes Tables fcbc_CapitalConservationBufferPhaseInAmount Capital Conservation Buffer Phase In Amount Amount resulting from the phase-in of a capital conservation buffer. Related Parties [Member] Represents related parties. us-gaap_GainLossOnSaleOfOtherAssets Loss on sale of other real estate owned fcbc_TierOneCapitalSecuritiesPhaseOutPeriod Tier One Capital Securities Phase Out Period Represents the phase out period for Tier 1 capital securities. Common equity Tier 1, to be well capitalized ratio The Common Equity Tier 1 Risk Based Capital ratio (Common Equity Tier 1 Capital divided by risk-weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. Common equity Tier 1, required ratio The minimum Common Equity Tier 1 Risk Based Capital Ratio (Common Equity Tier 1 Capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. Noninterest income, excluding net gain (loss) on sale of securities Amount of other operating income excluding gains (losses) on sale of securities. Return of capital from subsidiaries Amount of cash inflow (outflow) from equity method investment dividends or distributions return of capital. Covered loans Loans held for investment, covered Loss on extinguishment of debt Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Repayment and Penalties Securities held to maturity, fair value Total fair value us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Other operating expense Total other operating expense Federal funds sold Derivative Instruments, Gain (Loss) [Table Text Block] Interest expense Total interest expense us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Derivative Instruments and Hedging Activities Disclosure [Text Block] Subsequent Event [Member] Interest on long-term debt Subsequent Event Type [Axis] Subsequent Event Type [Domain] Interest on short-term borrowings us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive 2024 and thereafter us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense Deferred Compensation Arrangement with Individual, Compensation Expense Fair Value Measurement, Policy [Policy Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo 2020 Interest on deposits us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree 2021 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour 2022 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive 2023 us-gaap_DeferredCompensationArrangementWithIndividualRecordedLiability Deferred Compensation Arrangement with Individual, Recorded Liability Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths 2019 us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1 Finite-Lived Intangible Assets, Remaining Amortization Period Business Combinations Policy [Policy Text Block] us-gaap_FiniteLivedIntangibleAssetUsefulLife Finite-Lived Intangible Asset, Useful Life Earnings Per Share, Policy [Policy Text Block] Interest expense: Income Tax, Policy [Policy Text Block] Cash dividends received from subsidiary bank Interest income Total interest income Reclassification of certain tax effects fcbc_ReclassificationFromAociForStrandedTaxCurrentPeriodNetOfTaxAttributableToParent Amount after tax of reclassification adjustments for stranded tax of other comprehensive income (loss) attributable to parent. Interest on deposits in banks Schedule of Finite-Lived Intangible Assets [Table Text Block] us-gaap_LesseeOperatingLeaseTermOfContract Lessee, Operating Lease, Term of Contract Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] us-gaap_TimeDepositMaturitiesYearFour 2022 us-gaap_TimeDepositMaturitiesYearFive 2023 us-gaap_TimeDepositMaturitiesAfterYearFive 2024 and thereafter Interest on securities -- taxable Interest on securities -- tax-exempt us-gaap_TimeDepositMaturitiesYearOne 2019 us-gaap_TimeDepositMaturitiesYearTwo 2020 us-gaap_TimeDepositMaturitiesYearThree 2021 us-gaap_ImpairmentOfInvestments Net impairment losses recognized in earnings Time Deposit Maturities [Table Text Block] Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block] Interest and fees on loans us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments Deposit Liabilities, Collateral Issued, Financial Instruments Revenue from Contract with Customer [Policy Text Block] us-gaap_DeferredTaxAssetsValuationAllowance Deferred Tax Assets, Valuation Allowance, Total us-gaap_DeferredTaxAssetsNet Total deferred tax assets Interest income: us-gaap_DeferredTaxAssetsLiabilitiesNet Net deferred tax asset Individual retirement accounts us-gaap_DeferredTaxAssetsOther Other Money market accounts Savings deposits Goodwill and Intangible Assets, Policy [Policy Text Block] us-gaap_DeferredIncomeTaxLiabilities Total deferred tax liabilities Certificates of deposit Interest-bearing demand deposits CONNECTICUT Total noninterest income Interest-bearing deposits Noninterest income Unrealized losses on available-for-sale securities us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit Time Deposits, at or Above FDIC Insurance Limit Total contractual maturities IOWA us-gaap_BankOwnedLifeInsuranceIncome Bank owned life insurance Deposit Liabilities Disclosures [Text Block] Intangible assets Unrealized asset losses Noninterest income: Deferred loan fees Fully Phased-In [Member] Represents the fully phased in minimum Basel III requirements. us-gaap_RepurchaseAgreementCounterpartyWeightedAverageMaturityOfAgreements1 Repurchase Agreement Counterparty, Weighted Average Maturity of Agreements Provision for loan losses Provision for loan losses Provision (Recovery) for loan losses charged to operations Net interest income after provision Net interest income after provision for loan losses NEW JERSEY us-gaap_PropertyPlantAndEquipmentUsefulLife Property, Plant and Equipment, Useful Life Net interest income Net interest income Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block] NEW YORK OHIO Other income (expense) Allowance for loan losses TEXAS us-gaap_NumberOfOperatingSegments Number of Operating Segments Furniture and Fixtures [Member] us-gaap_NumberOfReportableSegments Number of Reportable Segments Building and Building Improvements [Member] us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation Deferred compensation assets WISCONSIN Land Improvements [Member] Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment, Type [Domain] Deposit Account [Member] Assets Deferred tax assets Net cash used in financing activities Net cash used in financing activities Other operating income Total other operating income Net cash provided by operating activities Net cash provided by operating activities Other Notional or contractual amount Net cash provided by investing activities Net cash provided by investing activities Net (decrease) increase in cash and cash equivalents Net (decrease) increase in cash and cash equivalents Derivatives, Policy [Policy Text Block] Odd days interest deferral Repurchase Agreements, Collateral, Policy [Policy Text Block] us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactions Total future minimum lease payments Net change in other financing activities fcbc_SalesPriceInExcessOfNetLiabilitiesAssumed Sales price in excess of net liabilities assumed Represents the sales price in excess of the net liabilities assumed in an acquisition. Total purchase price Net amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. Marketable Securities, Policy [Policy Text Block] Impaired loans, related allowance Excess tax benefit from equity-based compensation us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinThreeYears 2021 Fixed assets us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinFourYears 2022 us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinFiveYears 2023 us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsThereafter 2024 and thereafter Impaired loans with no related allowance, interest income recognized us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinOneYear 2019 Impaired loans with a related allowance, interest income recognized us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinTwoYears 2020 Deferred tax liabilities Interest income recognized us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod Interest income recognized Total impaired loans, interest income recognized Impaired loans with no related allowance, recorded investment us-gaap_PaymentsOfDividendsCommonStock Payments of common dividends Impaired loans with a related allowance, recorded investment us-gaap_ImpairedFinancingReceivableRecordedInvestment Impaired Financing Receivable, Recorded Investment, Total Total impaired loans, recorded investment Average recorded investment Impaired loans with no related allowance, average recorded investment Impaired loans with a related allowance, average recorded investment us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment Total impaired loans, average recorded investment Total sales price The cash outflow or inflow associated with the amount paid or received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period. Amount due remaining on books Amount of receivable due from or payable due to as part of consideration transferred in a divestiture of business. Impaired loans with no related allowance, unpaid principal balance Impaired loans with a related allowance, unpaid principal balance fcbc_PaymentsForProceedsFromDivestitureOfBusinessesNetOfCashDivested Net cash received in divestitures The cash outflow or inflow associated with the divestiture of businesses, net of cash divested. us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance Total impaired loans, unpaid principal balance Book value of assets sold Amount classified as assets sold (acquired) attributable to disposal group held for sale or disposed of. Noninterest expense Total noninterest expense us-gaap_PaymentsForRepurchaseOfCommonStock Payments for repurchase of treasury stock Book value of liabilities sold Amount classified as liabilities sold (incurred) attributable to disposal group held for sale or disposed of us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability Furniture and equipment expense FDIC premiums and assessments Proceeds from stock options exercised State Proceeds from issuance of common stock us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit State Noninterest expense: Federal us-gaap_DeferredFederalIncomeTaxExpenseBenefit Federal Deferred tax expense (benefit): Current tax expense (benefit): us-gaap_CurrentIncomeTaxExpenseBenefit Total current tax expense Class of Financing Receivable, Type [Domain] us-gaap_ReclassificationFromAociCurrentPeriodTax Income tax expense Class of Financing Receivable, Type [Axis] Financing Receivable Portfolio Segment [Domain] Income before income taxes Income before income taxes Income before income taxes Commercial Portfolio Segment [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] Financing Receivable Portfolio Segment [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Comprehensive Income (Loss) Note [Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Insurance commissions Repayments of FHLB and other borrowings, net Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] us-gaap_RepaymentsOfLongTermDebt Repayments of long-term debt Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Accounting Policies [Abstract] Basis of Accounting, Policy [Policy Text Block] fcbc_EffectiveIncomeTaxRateReconciliationAdjustmentFromBankOwnedLifeInsurancePercent Bank owned life insurance Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to bank owned life insurance expense. fcbc_EffectiveIncomeTaxRateReconciliationAdjustmentFromBankOwnedLifeInsuranceAmount Bank owned life insurance, amount Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to bank owned life insurance expense. Cash dividends per common share (in dollars per share) Common dividends declared, per share (in dollars per share) Reclassifications Reflects the amount of reclassification made to related parties in the form of loan and lease receivables. Other operating expense: Other operating income: Receivable Type [Axis] Receivable [Domain] Condensed Financial Information of Parent Company Only Disclosure [Text Block] Acquisitions in 2016 [Member] Represents all acquisitions during the year, 2016. Reclassification of Interchange Expense From Noninterest Expense to Net Against Interchange Income [Member] Represents the Reclassification of Interchange Expense From Noninterest Expense to Net Against Interchange Income. fcbc_NumberOfOfficesSold Number of Offices Sold Represents the number of offices sold. Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Increase (decrease) in accumulated other comprehensive loss Represents the increase in accumulated other comprehensive income in noncash investing or financing activities. fcbc_DividendsInExcessOfIncomeLossFromEquityMethodInvestments Dividends in excess of undistributed net income of subsidiaries This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes dividends in excess of income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee. Total dilutive effect of potential common shares (in shares) Interest, taxes, and other liabilities The aggregate amount of interest, taxes and other liabilities. fcbc_ExcessTaxBenefitFromSharebasedCompensation Excess tax benefit Amount of realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost . Designated Par Value [Member] Information pertaining to preferred stock with a designated par value. us-gaap_DueToOtherRelatedPartiesCurrentAndNoncurrent Due to Other Related Parties Antidilutive potential common shares (in shares) Undesignated Par Value [Member] Information pertaining to preferred stock with an undesignated par value. Weighted average diluted shares outstanding (in shares) Diluted (in shares) Weighted average common shares outstanding, diluted (in shares) Asset Class [Axis] Asset Class [Domain] Statement of Financial Position [Abstract] Diluted (in dollars per share) Diluted earnings per common share (in dollars per share) Weighted average common shares outstanding, basic (in shares) Basic (in shares) Other items, net us-gaap_EffectiveIncomeTaxRateContinuingOperations Income tax at the effective tax rate Business Acquisition [Axis] Basic (in dollars per share) Basic earnings per common share (in dollars per share) Business Acquisition, Acquiree [Domain] Deferred tax revaluation Statement of Cash Flows [Abstract] Statement of Stockholders' Equity [Abstract] us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome Tax-exempt interest income Repayments of securities sold under agreements to repurchase, net Schedule of Financing Receivables, Non Accrual Status [Table Text Block] Quarterly Financial Information [Table Text Block] Fiduciary and Trust [Member] Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Merger, acquisition, and divestiture expense Amount of merger, acquisition and divestiture expense. fcbc_AccretionOnAcquiredLoans Accretion on acquired loans Amount of accretion on acquired loans. Amortization of FDIC indemnification asset, net Net FDIC indemnification asset amortization Increases (decreases) to the indemnification asset due to accretion (amortization) of the loan discount relating to loss sharing agreements with the Federal Deposit Insurance Corporation (FDIC). Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Loans originated to finance other real estate Represents the amount of loans to finance the purchase of real estate. Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] (Payments to) proceeds from the FDIC Amount of cash inflow from Federal Deposit Insurance Corporation. Nondeductible goodwill impairment and disposition First Community Bank [Member] Information pertaining to First Community Bank. fcbc_NumberOfOperatingBranchesOfBank Number of Operating Branches of Bank Represents the number of operating branches of the bank. Realized Gain (Loss) on Investments [Table Text Block] Divestiture of Bank Branches to First Bank [Member] Information pertaining to the divestiture of bank branches to First Bank. North Carolina [Member] Information pertaining to the geographical location of North Carolina. Schedule of Available-for-sale Securities Reconciliation [Table Text Block] fcbc_NumberOfBranchesSold Number of Branches Sold Represents the number of branches sold. Bank of America [Member] Information pertaining to the Bank of America. Acquisition of Bank Branches from First Bank [Member] Information pertaining to the acquisition of bank branches from First Bank. (Decrease) increase in interest-bearing deposits, net Southwestern Virginia [Member] Information pertaining to the geographical location of southwestern Virginia. Increase (decrease) in noninterest-bearing deposits, net Loans to affiliates fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Receivable Amount of loans receivable acquired, at the acquisition date. us-gaap_LoansAndLeasesReceivableRelatedParties Beginning balance Ending balance State income tax, net of federal benefit Fair Value Measurements, Nonrecurring [Table Text Block] fcbc_PremiumReceivedOnDepositAccountsDisposedOfInBranchSale Premium Received on Deposit Accounts Disposed of in Branch Sale Represents the amount of premium received on deposit accounts disposed of in branch sale. Reclassification of Proceeds from Bank Owned Life Insurance from Operating Activities to Investing Activities [Member] Represents information pertaining to the reclassification of proceeds from bank owned life insurance from operating activities to investing activities. fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits Amount of deposits assumed at the acquisition date. us-gaap_PaymentsForProceedsFromOtherInvestingActivities Net change in other investing activities Other items, net, amount Financing activities fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets including Goodwill Amount of assets including goodwill acquired at the acquisition date. Federal income tax at the statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Deferred tax revaluation, amount Dividends in excess of undistributed net income of subsidiaries fcbc_PercentageOfCombinedDepreciationOfCombinedReportedValueOfAggregateSecuritiesPortfolio Percentage of Combined Depreciation of Combined Reported Value of Aggregate Securities Portfolio Represents the percentage of combined depreciation of combined reported value of aggregate securities portfolio. us-gaap_IncomeTaxReconciliationTaxExemptIncome Tax-exempt interest income, amount fcbc_NumberOfSecuritiesInUnrealizedLossPosition Number of Securities in Unrealized Loss Position Represents the number of securities in unrealized loss position. Proceeds from bank owned life insurance Mortgage-backed Agency Securities [Member] Information pertaining to mortgage-backed agency securities. Single Issue Trust Preferred Securities [Member] Information pertaining to single issue trust preferred securities. Net cash received in acquisitions and divestitures Cash proceeds from mergers, acquisitions, and divestitures, net Proceeds from divestitures Proceeds from Divestiture of Businesses us-gaap_CashDivestedFromDeconsolidation Cash sold us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities, Total us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired Net cash paid in acquisitions Nondeductible goodwill impairment and disposition, amount Class of Stock [Axis] Class of Stock [Domain] Cash acquired Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] us-gaap_PaymentsToAcquireBusinessesGross Payments to Acquire Businesses, Gross us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther Other liabilities Financial Service, Other [Member] us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable Deposits State income tax, net of federal benefit, amount us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment Premises and equipment us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets Other assets Federal income tax at the statutory rate, amount us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables Loans Income Tax Disclosure [Text Block] Hedging Designation [Axis] Hedging Designation [Domain] Designated as Hedging Instrument [Member] Schedule of Debt [Table Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Non-cash purchase price Share-based Compensation, Stock Options, Activity [Table Text Block] Pass [Member] Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Proceeds from maturities and calls of securities held to maturity us-gaap_GoodwillAndIntangibleAssetImpairment Goodwill and Intangible Asset Impairment, Total Proceeds from sale of securities available for sale Internal Credit Assessment [Axis] Proceeds from maturities, prepayments, and calls of securities available for sale Internal Credit Assessment [Domain] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Funded Status [Table Text Block] Proceeds from sale of other real estate owned Schedule of Expected Benefit Payments [Table Text Block] us-gaap_PaymentsToAcquireAvailableForSaleSecuritiesDebt Payments to acquire securities available for sale Construction, Development and Other Land [Member] Information pertaining to construction, development and other land loans. Schedule of Held to Maturity Debt Securities [Table Text Block] Tabular disclosure held to maturity debt securities. fcbc_NumberOfLoanPortfolioSegments Number of Loan Portfolio Segments Represents the number of loan portfolio segments. Single Family Non-owner Occupied [Member] Information pertaining to single family non-owner occupied loans. Non-farm, Non-residential [Member] Information pertaining to non-farm, non-residential loans. Commercial and Industrial [Member] Information pertaining to commercial and industrial loans. Multi-family Residential [Member] Information pertaining to multi-family residential loans. Farmland [Member] Information pertaining to farmland loans. Consumer Real Estate Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to consumer real estate receivables. Agricultural [Member] Information pertaining to agricultural loans. Goodwill and Intangible Assets Disclosure [Text Block] Schedule of Goodwill [Table Text Block] Home Equity Lines [Member] Information pertaining to home equity lines. Single Family Owner Occupied [Member] Information pertaining to single family owner occupied loans. Owner Occupied Construction [Member] Information pertaining to owner occupied construction. Other Loan [Member] Information pertaining to other loans. Consumer and Other Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to consumer and other receivables. Consumer Loans [Member] Information pertaining to consumer loans. Proceeds from sale of premises and equipment Retirement Plan Type [Axis] Service fees The amount of service fees during the period. Retirement Plan Type [Domain] Credit Facility [Axis] Credit Facility [Domain] Supplemental Employee Retirement Plan [Member] Special Mention [Member] Substandard [Member] Doubtful [Member] Unlikely to be Collected Financing Receivable [Member] Federal Deposit Insurance Corporation Indemnification Asset [Policy Text Block] Disclosure of accounting policy for indemnification assets relating to loss share agreements with the Federal Deposit Insurance Corporation (FDIC). us-gaap_PaymentsToAcquireProductiveAssets Payments to acquire premises and equipment Other Intangible Assets [Member] Dilutive effect of potential common shares (in shares) Transfer of loans to other real estate TDRs Financing Receivable, Modifications, Recorded Investment Weighted average shares outstanding Cash paid for income taxes Net (loss) gain on sale of securities Gain on sale of securities Total contracts, payment default Pre-modification recorded investment Post-modification recorded investment Supplemental disclosure -- cash flow information Recorded investment, payment default Total contracts Loan Restructuring Modification [Axis] Loan Restructuring Modification [Domain] Impaired Financing Receivables [Table Text Block] Troubled Debt Restructurings on Financing Receivables [Table Text Block] Core Deposits [Member] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Total loans Loans held for investment, net of unearned income (includes covered loans of $18,815 and $27,948, respectively) Total loans held for investment, net of unearned income Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans and leases covered under loss sharing agreements. Covered loans, percent Percent of loans and leases receivable covered by loss sharing agreements. Schedule of Covered Loans Held for Investment Net of Unearned Income [Table Text Block] Tabular disclosure of covered loans held for investment, net of unearned income. Non-covered loans, percent Percent before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. fcbc_LoansAndLeasesReceivableNetOfDeferredIncomeAndNetReportedAmountPercent Total loans held for investment, net of unearned income, percent Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes loans and leases covered under loss sharing agreements. Purchased Credit Impaired Loans [Member] Information pertaining to purchased credit impaired loans. Net income Net income Peoples Bank of Virginia [Member] Information pertaining to Peoples Bank of Virginia. Waccamaw Bank [Member] Information pertaining to Waccamaw Bank. us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Accretable Yield [Table Text Block] Tabular disclosure of certain loans acquired in transfer not accounted for as debt securities accretable yield. Financing Receivable Credit Quality Indicators [Table Text Block] Other Receivables [Member] Information pertaining to other receivables. Restricted Stock [Member] Current loans Employee Stock Option [Member] Other changes, net Amount of removals, extensions, and other events in the excess of a loan's cash flows expected to be collected over the investor's initial investment in acquired loans not accounted for as debt securities with evidence of deterioration of credit quality. Past due Total nonaccrual loans Financing Receivables, 30 to 59 Days Past Due [Member] Antidilutive Securities [Axis] Financing Receivables, 60 to 89 Days Past Due [Member] Antidilutive Securities, Name [Domain] Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Past Due Financing Receivables [Table Text Block] Financing Receivables, Period Past Due [Axis] Financing Receivables, Period Past Due [Domain] Financing Receivables [Text Block] Business Combination Disclosure [Text Block] fcbc_PercentageOfLoanLossCoveredByFDIC Percentage of Loan Loss Covered by FDIC Represents the percentage of loan covered by the FDIC. Schedule of Business Acquisitions, by Acquisition [Table Text Block] us-gaap_PaymentsForProceedsFromLoansAndLeases Proceeds from (originations of) loans, net Non-covered Loans [Member] Information pertaining to non-covered loans. Covered Loans [Member] Information pertaining to covered loans. fcbc_RestructuredLoansReserves Restructured Loans, Reserves Represents the amount of reserves for restructured loans. Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] FHLB advances us-gaap_FederalHomeLoanBankAdvancesWeightedAverageInterestRate us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock (Redemption of) proceeds from FHLB stock, net us-gaap_RelatedPartyDepositLiabilities Related Party Deposit Liabilities Decrease in other operating activities Investing activities Extinguishment of Debt, Type [Domain] Earnings per common share Earnings Per Share [Text Block] us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty Related Party Transaction, Expenses from Transactions with Related Party Investment in Federal Home Loan Bank (FHLB) and Federal Reserve Bank (FRB) Stock [Member] This item represents the amount shown on an entity's books for investments in Federal Home Loan Bank stock and Federal Reserve Bank stock. Discount range, impaired loans The measurement input for non-covered impaired loans. fcbc_MinimumPrincipalBalanceOfLoansForQuarterlyRatingReview Minimum Principal Balance of Loans for Quarterly Rating Review Minimum amount of principal for loans to be reviewed that are deemed to be impaired. Payments to (reimbursements from) the FDIC The amount of cash payments received (made) on FDIC indemnification asset. Other Investments [Policy Text Block] Disclosure of accounting policy for all other investments not included in marketable and nonmarketable securities. Extinguishment of Debt [Axis] Discount range, covered OREO The measurement input for covered other real estate owned. Discount range, non-covered OREO The measurement input for non-covered other real estate owned. Related Party Transactions Disclosure [Text Block] Schedule of Related Party Transactions [Table Text Block] Equipment, Computer Hardware and Software [Member] Represents all equipment, computer hardware, and software. fcbc_SaleOfBusinessEarnoutPaymentsToBeReceived Sale of Business Earn-out Payments to be Received Earn-out payments to be received from the divestiture of business. Insurance Service Segment [Member] Represents the insurance service disposal group. fcbc_SaleOfBusinessEarnoutPaymentsTerm Sale of Business Earn-out Payments Term The earn-out payment term from the divestiture of business. fcbc_ExpensesRelatedToDivestitureOfBusiness Expenses Related to Divestiture of Business Amount of incurred expenses as a result of the divestiture of business. fcbc_DisposalGroupIncludingDiscontinuedOperationGoodwillAndIntangibleAssets Disposal Group Including Discontinued Operation Goodwill And Intangible Assets Amount classified as goodwill and intangible assets attributable to disposal group held for sale or disposed of. fcbc_DisposalGroupIncludingDiscontinuedOperationLiabilitiesDeposits Disposal Group, Including Discontinued Operation, Liabilities, Deposits Amount classified as deposit liabilities attributable to disposal group held for sale or disposed of. fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedGoodwillAndIntangibleAssets Business Combination Recognized Identifiable Assets Acquired and Liabilities Assumed, Goodwill and Intangible Assets Amount of intangible assets and goodwill, acquired at the acquisition date. us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount Debt Instrument, Unused Borrowing Capacity, Amount fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherIntangibles Other intangible assets Amount of other intangible assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date. Pre-tax compensation expense Impaired Financing Receivables, Summarized Information [Table Text Block] Tabular disclosure of summarized information for impaired financing receivables. Changes in fair value Schedule of Impaired Financing Receivable, Average Recorded Investment and Interest Income Recognized [Table Text Block] Tabular disclosure of impaired financing receivable related to average recorded investment and interest income recognized. Trouble Debt Restructuring Accrual Status [Table Text Block] Tabular disclosure of accrual status related to trouble debt restructuring . Loans individually evaluated for impairment Loans collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Nonaccrual Recorded investment in financing receivables that have been modified by troubled debt restructurings and are on nonaccrual status as of the balance sheet date. Troubled Debt Restructurings [Member] Information pertaining to trouble debt restructurings. Allowance for loans individually evaluated Allowance for loans collectively evaluated Accrual Recorded investment in financing receivables that have been modified by troubled debt restructurings and are on accrual status as of the balance sheet date. Interest Income Related to Troubled Debt Restructurings [Table Text Block] Tabular disclosure of interest income related to troubled debt restructurings. us-gaap_ComprehensiveIncomeNetOfTax Total comprehensive income fcbc_NumberOfSecuritiesInUnrealizedLossPositionGreaterThanOrEqualToOneYear Number of Securities in Unrealized Loss Position, Greater than or Equal to One Year Number of investment positions that have been in a continuous unrealized loss position for greater than or equal to a year. Credit Loss Status [Axis] Other Real Estate Owned [Table Text Block] Tabular disclosure of other real estate owned. Credit Loss Status [Domain] Financial Asset Acquired with Credit Deterioration [Member] Purchase of treasury shares, shares (in shares) Common stock, outstanding (in shares) Preferred stock, outstanding (in shares) Allowance for Credit Losses on Financing Receivables [Table Text Block] Non-covered OREO secured by residential real estate Represents the amount of non-covered other real estate owned secured by residential real estate. us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Recoveries us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs Charge-offs us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet Net charge-offs us-gaap_DividendsCommonStockCash Common dividends declared Federal Home Loan Bank Borrowings [Member] Quarterly Financial Information [Text Block] Liability Class [Axis] Fair Value by Liability Class [Domain] us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue Balance Balance us-gaap_TreasuryStockValueAcquiredCostMethod Purchase of treasury shares Transfer of certain loans into Level 3 us-gaap_TreasuryStockValue Treasury stock us-gaap_StockRepurchasedDuringPeriodShares Stock Repurchased During Period, Shares Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] us-gaap_StockRepurchasedDuringPeriodValue Stock Repurchased During Period, Value Amortization of prior service cost us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses Amortization of losses us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Net periodic cost Service cost Interest cost Issuance of treasury stock to 401(k) plan Issuance of treasury stock to 401(k) plan, shares (in shares) Common stock options exercised, shares (in shares) Exercised (in shares) us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Common stock options exercised Equity-based compensation expense Granted (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod Canceled (in shares) Stock options granted (in shares) Total liabilities and stockholders' equity Total liabilities and stockholders' equity Reported Value Measurement [Member] Interest-bearing Deposits [Member] Retained earnings Accumulated other comprehensive loss Demand Deposits [Member] Measurement Input, Discount Rate [Member] Debt Disclosure [Text Block] us-gaap_OperatingLeaseLiability Operating Lease, Liability, Total us-gaap_OperatingLeaseRightOfUseAsset Operating Lease, Right-of-Use Asset Income before equity in undistributed net income of subsidiaries us-gaap_DeferredIncomeTaxExpenseBenefit Total deferred tax expense (benefit) Measurement Input Type [Axis] Measurement Input Type [Domain] Valuation, Market Approach [Member] Valuation Approach and Technique [Axis] Valuation Approach and Technique [Domain] us-gaap_StockOptionPlanExpense Issuance of treasury stock to 401(k) plan us-gaap_ShareBasedCompensation Equity-based compensation expense Total Fair Value us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Amortization of premiums on investments, net FHLB and other borrowings Cash and cash equivalents Non-cash sales price related to divestitures Non-cash sales price us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure Securities sold under agreements to repurchase Schedule of Available-for-sale and Held-to-maturity Municipal Securities By State [Table Text Block] Tabular disclosure of available-for-sale and held-to-maturity municipal securities categorized by state. All Other States [Member] All other States, not separately disclosed. Minnesota [Member] State of Minnesota. Massachusetts [Member] State of Massachusetts. Percent of Municipal Portfolio Represents the percentage of carrying value of municipal securities. Fair Value, Measurements, Nonrecurring [Member] Fair Value Measurement Inputs and Valuation Techniques [Table Text Block] Common stock, $1 par value; 50,000,000 shares authorized; 16,007,263 shares issued and outstanding at December 31, 2018; 21,381,779 shares issued and 4,383,553 shares in treasury at December 31, 2017 Common stock Municipal securities, amortized cost The cost of debt and equity securities, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any and the amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity. Adjustments to reconcile net income to net cash provided by operating activities Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Common stock, authorized (in shares) Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Common stock, issued (in shares) Common stock, par value (in dollars per share) Municipal securities, unrealized gains Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale and the amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity. Maturity Greater than 90 Days [Member] fcbc_AvailableForSaleAndHeldToMaturitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax Municipal securities, unrealized losses Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale and the amount of accumulated unrealized loss on investments in debt securities classified as held-to-maturity. Range [Domain] Maximum [Member] Supplemental transactions -- non-cash items Minimum [Member] Maturity Less than 30 Days [Member] Maturity 30 to 90 Days [Member] Municipal securities, fair value Amount of investment in debt and equity securities categorized as available-for-sale and the fair value of investments in debt securities classified as held-to-maturity. Weighted Average [Member] Product and Service [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Product and Service [Domain] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Range [Axis] us-gaap_CommonStockSharesHeldInEmployeeTrustShares Common Stock, Shares Held in Employee Trust, Shares us-gaap_OperatingLeasesRentExpenseNet Operating Leases, Rent Expense, Net, Total Preferred stock, undesignated par value; 1,000,000 shares authorized; Series A Noncumulative Convertible Preferred Stock, $0.01 par value; 25,000 shares authorized; none outstanding Preferred stock Cash paid for interest Preferred stock, no par value (in dollars per share) Geographical [Axis] Property, Plant and Equipment Disclosure [Text Block] Geographical [Domain] Property, Plant and Equipment [Table Text Block] Preferred stock, authorized (in shares) Portion at Fair Value Measurement [Member] [Default] Preferred stock, par value (in dollars per share) Estimate of Fair Value Measurement [Member] Measurement Basis [Axis] Fair Value, Inputs, Level 3 [Member] Fair Value Hierarchy and NAV [Domain] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value Hierarchy and NAV [Axis] Operating activities Statement [Line Items] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] Additional paid-in capital Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability Total off-balance sheet risk AOCI Attributable to Parent [Member] Stockholders' equity Liabilities: Schedule of Fair Value, Off-balance Sheet Risks [Table Text Block] Adjustments for Change in Accounting Principle [Axis] Adjustments for Change in Accounting Principle [Domain] Fair value loans Loans held for investment, net of allowance Assets: Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table Text Block] Fair Value, by Balance Sheet Grouping [Table Text Block] Total liabilities Total liabilities Reclassification of treasury stock Reclassification of Treasury Stock Amount of reclassification of treasury stock during the period. Reclassification of certain tax effects Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act. us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation Disposal Group, Including Discontinued Operation, Liabilities, Total Other liabilities Special common dividends declared, per share (in dollars per share) Aggregate special dividends declared during the period for each share of common stock outstanding. fcbc_SpecialDividendsCommonStockCash Special common dividend declared Amount of paid and unpaid special common stock dividends declared with the form of settlement in cash. Schedule of Other Operating Cost and Expense, by Component [Table Text Block] Accounting Standards Update 2014-09 [Member] fcbc_DeferredLoanFees Deferred Loan Fees Represents deferred loan fees. Derivative financial liabilities Derivative liabilities Accounting Standards Update 2016-02 [Member] Interest payable Parent Company [Member] Accounting Standards Update 2016-15 [Member] us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total Others [Member] Information pertaining to other banks not separately disclosed. Consolidated Entities [Axis] fcbc_PerformingStatusReturnedPeriod Performing Status Returned Period Represents the performing status return period. Consolidated Entities [Domain] Type of Adoption [Domain] Standby letters of credit and financial guarantees(1) Commitments to extend credit Adjustments for New Accounting Pronouncements [Axis] Condensed Cash Flow Statement [Table Text Block] Condensed Balance Sheet [Table Text Block] Condensed Income Statement [Table Text Block] Other Income and Other Expense Disclosure [Text Block] Twelve Months Ended December 31, 2016 [Member] Represents information about period of twelve months ended December 31, 2016. Retained Earnings [Member] Purchase of treasury shares, per share (in dollars per share) Treasury Stock [Member] Additional Paid-in Capital [Member] Common Stock [Member] fcbc_LoansDeemedToBeImpairedThreshold Loans Deemed to be Impaired, Threshold The quarterly review threshold for reviews of loans that are deemed to be impaired. Preferred Stock [Member] Report Date [Axis] Financial Statement Filing Date [Domain] Equity Components [Axis] Equity Component [Domain] FHLB borrowings Other Assets [Member] us-gaap_LineOfCredit Long-term Line of Credit, Total Changes due to principal reduction Amount of increase (decrease) of financial instrument due to reduction of principal classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. Balance Sheet Location [Axis] Balance Sheet Location [Domain] fcbc_DebtSecuritiesHeldtomaturityFairValueDisclosure Debt securities held to maturity Fair value of investment in debt security measured at amortized cost (held-to-maturity). Securities sold under agreements to repurchase Securities sold under agreements to repurchase Repurchase agreements us-gaap_BankOverdrafts Bank Overdrafts Deposits fair value Income Statement Location [Axis] Income Statement Location [Domain] Acquisitions in 2018 [Member] Information pertaining to acquisitions in 2018. Acquisitions in 2017 [Member] Information pertaining to acquisitions in 2017. Segments [Axis] Segments [Domain] Scenario, Forecast [Member] Statement [Table] Scenario [Axis] Scenario, Unspecified [Domain] us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent Other comprehensive (loss) income, before tax Income tax expense (benefit) us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1 Income Statement [Abstract] Other comprehensive income (loss) Other comprehensive income (loss), net Disposal Group Name [Axis] Disposal Group Name [Domain] Total borrowings us-gaap_InterestBearingDepositLiabilitiesDomestic us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss Securities available for sale, total unrealized losses Total deposits Total deposits Reclassification of Non-service Components of Net Period Benefit Costs From Salaries and Employee Benefits to Other Expense [Member] Related to a reclassification due to a new accounting pronouncement. us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Securities available for sale, less than 12 months, unrealized losses us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Securities available for sale, 12 months or longer, unrealized losses us-gaap_InterestBearingDepositLiabilities Interest-bearing deposits Total interest-bearing deposits us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet Impairment losses on securities Net impairment losses recognized in earnings Noninterest-bearing demand deposits Noninterest-bearing deposits us-gaap_TimeDeposits Total contractual maturities Equity securities Equity securities Securities available for sale, less than 12 months, fair value Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Table Text Block] us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent Net unrealized (losses) gains on available-for-sale debt securities Securities available for sale, 12 months or longer, fair value Securities available for sale, total fair value Deposit Liabilities, Type [Table Text Block] us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax Reclassification adjustment for net loss (gain) recognized in net income Reclassification adjustment for other-than-temporary impairment losses recognized in net income Change in net unrealized (losses) gains on securities without other-than-temporary impairment us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax Net unrealized gains (losses) on employee benefit plans Available-for-sale debt securities: Reclassification adjustment for amortization of prior service cost and net actuarial loss recognized in net income us-gaap_OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax Plan change us-gaap_SecurityOwnedAndPledgedAsCollateralFairValue Security Owned and Pledged as Collateral, Fair Value, Total Net actuarial (loss) gain Employee benefit plans: Total stockholders' equity Total stockholders' equity Balance Balance FHLB advances us-gaap_LongtermFederalHomeLoanBankAdvancesNoncurrent Long-term Federal Home Loan Bank Advances, Noncurrent us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax Securities available for sale, unrealized losses Securities available for sale, unrealized gains Interest Rate Swap [Member] Securities available for sale, amortized cost Securities available for sale, due after one year but within five years, amortized cost Securities available for sale, due after five years but within ten years, amortized cost Securities available for sale, due after ten years, amortized cost