Document And Entity Information us-gaap_PaymentsForProceedsFromLoansAndLeases Proceeds from (originations of) loans, net Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Note To Financial Statement Details Textual Financing Receivables, 60 to 89 Days Past Due [Member] statementsignificantaccountingpoliciespolicies statementnote2investmentsecuritiestables Securities held to maturity, fair value Securities held to maturity, fair value Securities held to maturity London Interbank Offered Rate (LIBOR) [Member] statementnote3loanstables Interest expense Financing Receivables, Period Past Due [Domain] statementnote4creditqualitytables Financing Receivables, Period Past Due [Axis] statementnote5allowanceforloanlossestables Securities held to maturity Securities held to maturity, amortized cost Securities held to maturity Financing Receivables, 30 to 59 Days Past Due [Member] statementnote6fdicindemnificationassettables Financing Receivables [Text Block] Variable Rate [Domain] statementnote7depositstables Variable Rate [Axis] statementnote8borrowingstables statementnote9derivativeinstrumentsandhedgingactivitiestables Past Due Financing Receivables [Table Text Block] statementnote10employeebenefitplanstables statementnote11accumulatedothercomprehensiveincometables us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral Available-for-sale Securities Pledged as Collateral statementnote12fairvaluetables statementnote13earningspersharetables statementnote14litigationcommitmentsandcontingenciestables us-gaap_InterestAndDividendIncomeOperating Total interest income statementnote2investmentsecuritiessecuritiesavailableforsaledetails Interest on deposits in banks statementnote2investmentsecuritiessecuritiesheldtomaturitydetails statementnote2investmentsecuritiessecuritiesbycontractualmaturitydetails Securities available for sale Securities available for sale, fair value Securities available for sale statementnote2investmentsecuritiesavailableforsalesecuritiesincontinuousunrealizedlosspositiondetails statementnote2investmentsecuritiesheldtomaturitysecuritiesincontinuousunrealizedlosspositiondetails statementnote2investmentsecuritiesgrossrealizedgainsandlossesfromsaleofsecuritiesdetails statementnote3loansloansbyclassdetails statementnote3loanscoveredloansbyclassdetails statementnote3loanspciloansdetails statementnote3loansactivityinaccretableyieldonpciloansdetails statementnote4creditqualityloansbycreditqualitydetails statementnote4creditqualityrecordedinvestmentandinterestincomerecognizedonimpairedloansexcludingpurchasedcreditimpairedloansdetails statementnote4creditqualityaverageannualrecordedinvestmentandinterestincomerecognizedonimpairedloansexcludingpurchasedcreditimpairedloansdetails statementnote4creditqualityinformationonimpairedpciloanpoolsdetails statementnote4creditqualitynonaccrualloansbyloanclassdetails us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock Proceeds from (payments for) FHLB stock, net statementnote4creditqualityagingofpastdueloansbyloanclassdetails statementnote4creditqualityloansmodifiedastroubleddebtrestructuringsbyloanclassandaccrualstatusdetails statementnote4creditqualitybalanceandinterestincomerelatedtoimpairedloanpoolsdetails statementnote4creditqualityloansmodifiedastroubledebtrestructuringsdetails statementnote4creditqualityotherrealestateowneddetails statementnote5allowanceforloanlosseschangesinallowanceforloanlossesdetails (Increase) decrease in other operating activities statementnote5allowanceforloanlossesallowanceforloanlossesandrecordedinvestmentinloansevaluatedforimpairmentexcludingpciloansdetails statementnote5allowanceforloanlossesallowanceforloanlossesonpciloansandrecordedinvestmentdetails Long-term FHLB advances, rate us-gaap_FederalHomeLoanBankAdvancesWeightedAverageInterestRate Investing activities statementnote6fdicindemnificationassetchangesinreceivablefromfdicdetails statementnote7depositscomponentsofdepositsdetails statementnote8borrowingscomponentsofborrowingsdetails Reported Value Measurement [Member] statementnote8borrowingscontractualandweightedaveragematuritiesoflongtermborrowingsdetails statementnote8borrowingscontractualmaturitiesofrepurchaseagreementsdetails Interest on securities -- taxable statementnote9derivativeinstrumentsandhedgingactivitiesnotionalorcontractualamountsandfairvaluesofderivativefinancialinstrumentsdetails statementnote9derivativeinstrumentsandhedgingactivitieseffectofderivativeandhedgingactivityonconsolidatedstatementsofincomedetails statementnote10employeebenefitplansnetperiodicbenefitcostdetails Interest on securities -- tax-exempt statementnote11accumulatedothercomprehensiveincomecomponentsofaccumulatedothercomprehensiveincomenetoftaxdetails statementnote11accumulatedothercomprehensiveincomereclassificationsoutofaccumulatedothercomprehensiveincomedetails statementnote12fairvalueassetsandliabilitiesmeasuredatfairvalueonrecurringbasisdetails statementnote12fairvalueassetsmeasuredatfairvalueonnonrecurringbasisdetails statementnote12fairvaluequantitativeinformationforassetsmeasuredatfairvalueonnonrecurringbasisdetails statementnote12fairvaluefinancialinstrumentsdetails Interest and fees on loans statementnote13earningspersharebasicanddilutedearningspercommonsharedetails statementnote14litigationcommitmentsandcontingenciesoffbalancesheetfinancialinstrumentsdetails Interest-bearing Deposits [Member] Notes To Financial Statements Notes To Financial Statements [Abstract] Demand Deposits [Member] us-gaap_ComprehensiveIncomeNetOfTax Total comprehensive income fcbc_DeferredLoansFees Deferred Loans Fees Represents the amount of deferred loan fees. 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. Purchase of treasury shares, shares (in shares) Preferred stock, shares outstanding (in shares) Use of Estimates, Policy [Policy Text Block] 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. us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Commercial and Industrial [Member] Information pertaining to commercial and industrial loans. New Accounting Pronouncements, Policy [Policy Text Block] 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. Reclassification, Policy [Policy Text Block] Agricultural [Member] Information pertaining to agricultural loans. Home Equity Lines [Member] Information pertaining to home equity lines. Interest income 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. Consolidation, Policy [Policy Text Block] 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. Consumer and Other Portfolio Segment [Member] Portfolio segment of the company's total financing receivables related to consumer and other receivables. Allowance Excluding Purchased Credit Impaired Loans [Member] Information pertaining to the allowance excluding purchased credit impaired loans. Consumer Loan [Member] Information pertaining to consumer loans. Basis of Accounting [Text Block] 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. Benefit attributable to the FDIC indemnification asset Represents the amount of provision (benefit) for loan losses. 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_DividendsCommonStockCash Common dividends declared 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. Cash and due from banks Interest-bearing deposits in banks Schedule of Information Related to Purchased Credit Impaired Loans [Table Text Block] Tabular disclosure of information related to purchased credit impaired loans. Waccamaw Commercial [Member] Information pertaining to Waccamaw Commercial loans. Debt Disclosure [Text Block] Waccamaw Serviced Home Equity Lines [Member] Information pertaining to Waccamaw serviced home equity lines. Waccamaw Residential [Member] Information pertaining to Waccamaw residential loans. Equity-based compensation expense Peoples Commercial [Member] Information pertaining to Peoples Commercial loans. Other Commercial Loan [Member] Information pertaining to other commercial loans. 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. Acquired impaired loans evaluated for impairment Represents the amount of acquired impaired loans evaluated for impairment. Discount range fcbc_PercentageOfLossCoveredByFDIC Percentage of Loss Covered by FDIC Represents the percentage of loss covered by the FDIC. Reimbursable expenses 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). us-gaap_TreasuryStockValueAcquiredCostMethod Purchase of treasury shares Securities held to maturity, total fair value Unsecured Line of Credit [Member] Information pertaining to the unsecured line of credit. us-gaap_TreasuryStockValue Treasury stock, at cost Below Market Interest Rate [Member] Information pertaining to below market interest rates. Other debt fcbc_DebtInstrumentCarryingAmountOfOther Amount, before unamortized (discount) premium and debt issuance costs, of other long-term debt. Wholesale Repurchase Agreements [Member] Information pertaining to wholesale repurchase agreements. Securities held to maturity, 12 months or longer fair value Securities held to maturity, less than 12 months fair value Long-term Advances [Member] Information pertaining to long-term advances. Retail Repurchase Agreements [Member] Information pertaining to retail repurchase agreements. Weighted average contractual rate fcbc_WeightedAverageContractualRate Represents the weighted average contractual rate. Interest receivable Weighted average maturity (in years) (Year) Represents the weighted average contractual maturity period. 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. Federal Home Loan Bank Borrowings [Member] Fair Value by Liability Class [Domain] Junior Subordinated Debt [Member] Liability Class [Axis] us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments Deposit Liabilities, Collateral Issued, Financial Instruments Total loans Total loans 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. Subordinated Debt [Member] Issuance of treasury stock to 401(k) plan, shares (in shares) 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. Issuance of treasury stock to 401(k) plan Fair Value Inputs, Assets, Quantitative Information [Table Text Block] 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. Securities held to maturity, due after ten years, fair value Purchased Credit Impaired Loans [Member] Information pertaining to purchased credit impaired loans. Securities held to maturity, due after five years but within ten years, fair value Restricted stock awards, shares (in shares) Loans individually evaluated for impairment Common stock options exercised, shares (in shares) Peoples Bank of Virginia [Member] Information pertaining to Peoples Bank of Virginia. us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet Decrease in accrued interest receivable Interest and Fees on Loans [Member] Primary financial statement caption encompassing interest and fees on loans. Securities held to maturity, due after one year but within five years, fair value Loans collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Waccamaw Bank [Member] Information pertaining to Waccamaw Bank. Securities held to maturity, due within one year, fair value Common stock options exercised Supplemental transactions -- noncash items Supplemental Executive Retention Plan [Member] Information pertaining to the supplemental executive retention plan (SERP). Securities held to maturity, due after one year but within five years, amortized cost Restricted stock awards 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. Securities held to maturity, due within one year, amortized cost Other Receivables [Member] Information pertaining to other receivables. Allowance for loans collectively evaluated Securities held to maturity, due after ten years, amortized cost Allowance for loans individually evaluated Securities held to maturity, due after five years but within ten years, amortized cost Decrease in estimated losses on covered loans Receivables Acquired with Deteriorated Credit Quality [Domain] us-gaap_ImpairmentOfInvestments Impairment losses on securities Receivables Acquired with Deteriorated Credit Quality [Axis] 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. Receivables Acquired with Deteriorated Credit Quality [Member] Savings deposits FDIC indemnification asset Beginning balance Ending balance us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Securities held to maturity, 12 months or longer unrealized losses Individual retirement accounts Allowance for Credit Losses on Financing Receivables [Table Text Block] Certificates of deposit Securities held to maturity, unrealized gains us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss Held-to-maturity Securities, Accumulated Unrecognized Holding Loss Securities held to maturity, unrealized losses Interest-bearing demand deposits Money market accounts us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Securities held to maturity, less than 12 months unrealized losses us-gaap_OtherRealEstate Total OREO Recoveries Deferred compensation liabilities Fair value portion of deferred compensation liabilities. Allowance for loan losses related to PCI loan pools Non-covered OREO Other real estate owned, non-covered Interest-bearing deposits: Deferred compensation assets Fair value portion of deferred compensation assets. fcbc_PercentageOfLoanLossCoveredByFDIC Percentage of Loan Loss Covered by FDIC Represents the percentage of loan covered by the FDIC. Impaired Loans [Member] Information pertaining to impaired loans. Covered OREO Other real estate owned, covered Other Real Estate, Covered Deposit Liabilities Disclosures [Text Block] Non-covered Loans [Member] Information pertaining to non-covered loans. Unobservable input Description of unobservable input used to measure fair value. Covered Loans [Member] Information pertaining to covered loans. us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet Net recoveries (charge-offs) Held-to-maturity Securities [Table Text Block] us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders' equity OREO [Member] Information pertaining to other real estate owned (OREO). fcbc_RestructuredLoansReserves Restructured Loans, Reserves Represents the amount of reserves for restructured loans. Retained earnings us-gaap_LoansAndLeasesReceivableAllowance Less: allowance for loan losses Beginning balance Ending balance us-gaap_LoansAndLeasesReceivableNetReportedAmountCoveredAndNotCovered Loans held for investment, net us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs Charge-offs Accumulated other comprehensive loss Savings Deposits [Member] Information pertaining to savings deposits. Non-covered loans Non-covered Reserve for unfunded commitments Represents the amount of reserve for unfunded credit commitments. Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block] Allowance for loan losses related to TDRs Represents the amount of allowance for loan losses. us-gaap_NoninterestIncome Total noninterest income Noninterest income us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss Net interest income after provision for loan losses Provision for loan losses Provision for (recovery of) loan losses Provision (Recovery) for loan losses charged to operations us-gaap_NumberOfOperatingSegments Number of Operating Segments Covered loans Covered Loans and Leases Receivable, Gross, Carrying Amount, Covered us-gaap_InterestIncomeExpenseNet Net interest income Loans held for investment, net of unearned income Derivative Instruments, Gain (Loss) [Table Text Block] Service charges on deposits Derivative Instruments and Hedging Activities Disclosure [Text Block] us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Net periodic cost Federal funds sold Interest cost Service cost us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Amortization of prior service cost us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses Amortization of losses Fair Value, Measurements, Nonrecurring [Member] Fair Value, Measurements, Recurring [Member] Valuation technique Fair Value, Measurement Frequency [Domain] Measurement Frequency [Axis] Impaired Financing Receivables, Summarized Information [Table Text Block] Tabular disclosure of summarized information for impaired financing receivables. 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 . 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. Impaired PCI loan pools Represents the number of impaired loans. Other operating income Troubled Debt Restructurings [Member] Information pertaining to trouble debt restructurings. Treasury stock, shares (in shares) 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. Amendment Flag FHLB and other borrowings Common stock, $1 par value; 50,000,000 shares authorized; 21,381,779 shares issued at September 30, 2017, and December 31, 2016; 4,395,277 and 4,387,571 shares in treasury at September 30, 2017, and December 31, 2016, respectively us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure Securities sold under agreements to repurchase Other Real Estate Owned [Table Text Block] Tabular disclosure of other real estate owned. Common stock, shares authorized (in shares) Common stock, shares issued (in shares) us-gaap_StockOptionPlanExpense Issuance of treasury stock to 401(k) plan Common stock, par value (in dollars per share) 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_ShareBasedCompensation Equity-based compensation expense us-gaap_RestrictedStockExpense Restricted stock awards Fair Value, Measurement Inputs, Disclosure [Text Block] Current Fiscal Year End Date Document Fiscal Period Focus Document Fiscal Year Focus Document Period End Date 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 us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Amortization of premiums on investments, net Document Type Other comprehensive income 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us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent Net unrealized (losses) gains on available-for-sale securities Total Fair Value Entity [Domain] Legal Entity [Axis] 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_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax Reclassification adjustment for net losses recognized in net income Reclassification adjustment for amortization of prior service cost and net actuarial loss recognized in net income us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax Net unrealized gains on employee benefit plans Entity Common Stock, Shares Outstanding (in shares) Additional paid-in capital Insurance commissions us-gaap_ReclassificationFromAociCurrentPeriodTax Income tax 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dividends Financial Instrument [Axis] us-gaap_PaymentsForRepurchaseOfCommonStock Payments for repurchase of treasury stock Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 1 [Member] Retained Earnings [Member] Fair Value, Inputs, Level 3 [Member] Additional Paid-in Capital [Member] us-gaap_LineOfCredit Long-term Line of Credit Treasury Stock [Member] Proceeds from stock options exercised Fair Value Hierarchy [Domain] Common dividends declared, per share (in dollars per share) Cash dividends per common share (in dollars per share) Fair Value, Hierarchy [Axis] Subordinated debt us-gaap_SubordinatedDebt Equity Component [Domain] Preferred Stock [Member] Common Stock [Member] Impaired loans, related allowance Interest income recognized us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod Interest income recognized Total impaired loans, interest income recognized Impaired loans with a related allowance, interest income recognized Equity Components [Axis] us-gaap_ImpairedFinancingReceivableRecordedInvestment Total impaired loans, recorded investment Impaired loans with a related allowance, recorded investment Impaired loans with no related allowance, interest income recognized Allowance for Credit Losses [Text Block] us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment Total impaired loans, average recorded investment Impaired loans with a related allowance, average recorded investment Impaired loans with no related allowance, recorded investment Recorded investment PCI loans, unpaid principal balance Total impaired loans, unpaid principal balance Impaired loans with a related allowance, unpaid principal balance Average recorded investment Impaired loans with no related allowance, average recorded investment Impaired loans with no related allowance, unpaid principal balance Unpaid principal balance Securities sold under agreements to repurchase Securities sold under agreements to repurchase Repurchase agreements Asset Class 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Interest-bearing Total interest-bearing deposits Gross realized gains Investments Classified by Contractual Maturity Date [Table Text Block] Realized Gain (Loss) on Investments [Table Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Notional or contractual amount Derivative, Notional Amount Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Deposit Liabilities, Type [Table Text Block] Repayments of securities sold under agreements to repurchase, net Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Fair Value Measurements, Nonrecurring [Table Text Block] Income tax expense us-gaap_PolicyTextBlockAbstract Accounting Policies Corporate Debt Securities [Member] Debt Securities [Member] US States and Political Subdivisions Debt Securities [Member] Net impairment losses recognized in earnings Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net Net impairment losses recognized in earnings Credit Facility [Domain] Major Types of Debt and Equity Securities [Domain] Increase in noninterest-bearing deposits, net Statement [Table] Major Types of Debt and Equity Securities [Axis] Decrease in interest-bearing deposits, net Credit Facility [Axis] Income Statement [Abstract] Financing activities Class of Stock [Domain] Class of Stock [Axis] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Long-term FHLB advances, amount us-gaap_LongtermFederalHomeLoanBankAdvancesNoncurrent Unlikely to be Collected Financing Receivable [Member] us-gaap_PaymentsForProceedsFromBusinessesAndInterestInAffiliates Cash proceeds from mergers, acquisitions, and divestitures, net Special Mention [Member] Doubtful [Member] Substandard [Member] Net loss on sale of securities Loss on sale of securities Net gain (loss) on sale of securities Designated as Hedging Instrument [Member] Hedging Designation [Domain] Hedging Designation [Axis] Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Debt [Table Text Block] Bank Time Deposits [Member] Salaries and employee benefits Collateralized Mortgage Backed Securities [Member] Derivative Contract [Domain] Derivative Instrument [Axis] Schedule of Net Benefit Costs [Table Text Block] Commitments and Contingencies Disclosure [Text Block] Net gain on divestitures Gain on divestiture, net us-gaap_GainLossOnSaleOfPropertyPlantEquipment Loss on sale of property, plant, and equipment, net Proceeds from maturities and calls of securities held to maturity Retirement Plan Name [Axis] Proceeds from maturities, prepayments, and calls of securities available for sale Proceeds from sale of securities available for sale Retirement Plan Name [Domain] Residential real estate loans in the foreclosure process(1) Proceeds from sale of other real estate Pass [Member] Long-term Debt, Type [Axis] Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Table Text Block] Long-term Debt, Type [Domain] Internal Credit Assessment [Domain] us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield Beginning balance Ending balance Internal Credit Assessment [Axis] us-gaap_PaymentsToAcquireAvailableForSaleSecurities Payments to acquire securities available for sale Interest, taxes, and other liabilities The aggregate amount of interest, taxes and other liabilities. Reclassifications from nonaccretable difference(1) Designated Par Value [Member] Information pertaining to preferred stock with a designated par value. Increase in estimated losses on covered OREO Undesignated Par Value [Member] Information pertaining to preferred stock with an undesignated par value. us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAccretion Accretion Amortization of intangibles PCI loans, recorded investment Dilutive effect of potential common shares (in shares) Weighted average shares outstanding us-gaap_FDICIndemnificationAssetCashPaymentsReceived Reimbursements from the FDIC Extinguishment of Debt, Type [Domain] FDIC Indemnification Asset Roll Forward [Table Text Block] Depreciation and amortization of property, plant, and equipment us-gaap_PaymentsForProceedsFromProductiveAssets Payments to acquire property, plant, and equipment, net Liabilities Net income available to common shareholders Net income available to common shareholders Extinguishment of Debt [Axis] us-gaap_Assets Total assets Occupancy expense Loans, Notes, Trade and Other Receivables Disclosure [Text Block] us-gaap_GainLossOnSaleOfOtherAssets Loss on sale of other real estate Merger, acquisition, and divestiture expense Amount of merger, acquisition and divestiture expense. fcbc_AccretionOnAcquiredLoans Accretion on acquired loans Amount of accretion on acquired loans. Portion of loss recognized in other comprehensive income Amount of portion of loss recognized in other comprehensive income. 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). Net income Net income Loans originated to finance other real estate Represents the amount of loans to finance the purchase of real estate. Dividends on preferred stock Proceeds from the FDIC Amount of cash inflow from Federal Deposit Insurance Corporation. us-gaap_DebtInstrumentTerm Debt Instrument, Term Other assets us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount Debt Instrument, Unused Borrowing Capacity, Amount Significant Accounting Policies [Policy Text Block] Disclosure of accounting policy for significant accounting policies. Other intangible assets Restricted Stock [Member] TDRs Financing Receivable, Modifications, Recorded Investment Antidilutive Securities, Name [Domain] Employee Stock Option [Member] Other operating expense Transfer of loans to other real estate us-gaap_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 Financing Receivable, Modifications, Subsequent Default, Recorded Investment Antidilutive Securities [Axis] Total contracts Post-modification recorded investment Statement of Comprehensive Income [Abstract] Pre-modification recorded investment us-gaap_InterestExpense Total interest expense Loan Restructuring Modification [Axis] 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. Supplemental disclosure -- cash flow information Cash paid for income taxes fcbc_NumberOfSecuritiesInUnrealizedLossPosition Number of Securities in Unrealized Loss Position Represents the number of securities in unrealized loss position. Loan Restructuring Modification [Domain] Investments [Domain] Investment Type [Axis] 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. Impaired Financing Receivables [Table Text Block] Goodwill Premises and equipment, net Troubled Debt Restructurings on Financing Receivables [Table Text Block] Interest on long-term debt Subordinated debt, rate us-gaap_DebtWeightedAverageInterestRate us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Interest on short-term borrowings us-gaap_TableTextBlock Notes Tables Financing Receivable Credit Quality Indicators [Table Text Block] Interest on deposits Current loans IRLCs Derivative assets us-gaap_FinancingReceivableRecordedInvestment90DaysPastDueAndStillAccruing Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Total nonaccrual loans Past due Earnings Per Share [Text Block] Earnings per common share