Document And Entity Information Securities available for sale, due after ten years, fair value 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 - Debt Securities Securities available for sale, due within one year, amortized cost Note 3 - Loans us-gaap_AvailableForSaleSecuritiesDebtMaturitiesSingleMaturityDate Securities available for sale, single maturity date, fair value Note 4 - Credit Quality Securities available for sale, due within one year, fair value Note 5 - Allowance for Loan Losses Securities available for sale, due after one year but within five years, fair value Note 6 - FDIC Indemnification Asset Securities available for sale, due after five years but within ten years, fair value Note 7 - Deposits Collateralized Mortgage Backed Securities [Member] Note 8 - Borrowings Note 9 - Derivative Instruments and Hedging Activities Note 10 - Employee Benefit Plans Note 11 - Earnings Per Share Note 12 - Accumulated Other Comprehensive Income (Loss) Hedging Designation [Axis] Note 13 - Fair Value Hedging Designation [Domain] Note 14 - Litigation, Commitments, and Contingencies Designated as Hedging Instrument [Member] Schedule of Maturities of Long-term Debt [Table Text Block] Note 2 - Debt Securities - Securities Available-for-sale (Details) Schedule of Debt [Table Text Block] Note 2 - Debt Securities - Securities Held to Maturity (Details) Note 2 - Debt Securities - Securities by Contractual Maturity (Details) Note 2 - Debt Securities - Available For Sale Securities in Continuous Unrealized Loss Position (Details) Note 2 - Debt Securities - Held to Maturity Securities in Continuous Unrealized Loss Position (Details) Note 3 - Loans - Loans by Class (Details) Note 3 - Loans - Covered Loans by Class (Details) Note 3 - Loans - PCI loans (Details) Note 3 - Loans - Activity in Accretable Yield on PCI loans (Details) US States and Political Subdivisions Debt Securities [Member] Note 4 - Credit Quality - Loans by Credit Quality (Details) Note 4 - Credit Quality - Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) Note 4 - Credit Quality - Average Annual Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) Note 4 - Credit Quality - Information on Impaired PCI Loan Pools (Details) Note 4 - Credit Quality - Nonaccrual Loans by Loan Class (Details) Note 4 - Credit Quality - Aging of Past Due Loans by Loan Class (Details) Note 4 - Credit Quality - Loans Modified as Troubled Debt Restructurings by Loan Class and Accrual Status (Details) Note 4 - Credit Quality - Balance and Interest Income Related to Impaired Loan Pools (Details) Pass [Member] Note 4 - Credit Quality - Other Real Estate Owned (Details) Note 5 - Allowance for Loan Losses - Changes in Allowance for Loan Losses (Details) US Treasury Securities [Member] Note 5 - Allowance for Loan Losses - Allowance for Loan Losses and Recorded Investment in Loans, Evaluated for Impairment Excluding PCI Loans, by Loan Class (Details) Note 5 - Allowance for Loan Losses - Allowance for Loan Losses on PCI Loans and Recorded Investment (Details) Note 6 - FDIC Indemnification Asset - Changes in Receivable From FDIC (Details) Note 7 - Deposits - Components of Deposits (Details) us-gaap_DerivativeTermOfContract Derivative, Term of Contract Note 8 - Borrowings - Components of Borrowings (Details) Schedule of Derivative Instruments [Table Text Block] Note 8 - Borrowings - Contractual and Weighted Average Maturities of Long-term Borrowings (Details) Other comprehensive loss before reclassifications Note 8 - Borrowings - Contractual Maturities of Repurchase Agreements (Details) US Government Agencies Debt Securities [Member] us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent Reclassified from AOCI Internal Credit Assessment [Axis] Proceeds from maturities, prepayments, and calls of securities available for sale Note 9 - Derivative Instruments and Hedging Activities - Notional or Contractual Amounts and Fair Values of Derivative Financial Instruments (Details) Internal Credit Assessment [Domain] Note 9 - Derivative Instruments and Hedging Activities - Effect of Derivative and Hedging Activity, on Consolidated Statements of Income (Details) Corporate Debt Securities [Member] Note 10 - Employee Benefit Plans - Components of Net Periodic Pension Cost and Assumed Discount Rate (Details) Note 11 - Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details) Note 12 - Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) Note 12 - Accumulated Other Comprehensive Income (Loss) - Reclassifications Out of Accumulated Other Comprehensive Income (Details) Note 13 - Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) Note 13 - Fair Value - Assets Measured at Fair Value on Nonrecurring Basis (Details) Note 13 - Fair Value - Quantitative Information for Assets Measured at Fair Value on Nonrecurring Basis (Details) Note 13 - Fair Value - Financial Instruments (Details) Note 14 - Litigation, Commitments and Contingencies - Off-balance Sheet Financial Instruments (Details) Schedule of Net Benefit Costs [Table Text Block] Notes To Financial Statements Notes To Financial Statements [Abstract] Proceeds from sale of other real estate owned Amortization us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax Net income us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax 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. Financial Instruments [Domain] 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. Financial Instrument [Axis] Agricultural [Member] Information pertaining to agricultural loans. Home Equity Lines [Member] Information pertaining to home equity lines. Securities available for sale, no single maturity date, fair value 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. 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. Securities available for sale, no single maturity date, amortized cost Consumer Loans [Member] Information pertaining to consumer loans. 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. Proceeds from premises and equipment 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. Service fees The amount of service fees during the period. Credit Facility [Axis] Credit Facility [Domain] 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 fcbc_InterchangeExpense Interchange Expense The amount of interchange expense due to credit and debit card transactions during the period. Special Mention [Member] Substandard [Member] Doubtful [Member] fcbc_IncreaseDecreaseInAccumulatedOtherComprehensiveIncome (Increase) decrease in accumulated other comprehensive loss Represents the increase (decrease) in accumulated other comprehensive income in noncash investing or financing activities. Unlikely to be Collected Financing Receivable [Member] us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield Beginning balance Ending balance us-gaap_PaymentsToAcquireProductiveAssets Payments to acquire premises and equipment 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. Dilutive effect of potential common shares (in shares) Transfer of loans to other real estate owned PCI loans, unpaid principal balance Waccamaw Serviced Home Equity Lines [Member] Information pertaining to Waccamaw serviced home equity lines. Allowance for Credit Losses [Text Block] PCI loans, recorded investment Waccamaw Residential [Member] Information pertaining to Waccamaw residential loans. Peoples Commercial [Member] Information pertaining to Peoples Commercial loans. Other Commercial Loan [Member] Information pertaining to other commercial loans. TDRs Financing Receivable, Modifications, Recorded Investment Weighted average shares outstanding 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. Cash paid for income taxes 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. Liabilities 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_FinancingReceivableModificationsSubsequentDefaultRecordedInvestment1 Financing Receivable, Modifications, Subsequent Default, Recorded Investment us-gaap_Assets Total assets Supplemental disclosure -- cash flow information Unsecured Line of Credit [Member] Information pertaining to the unsecured line of credit. us-gaap_FinancingReceivableModificationsNumberOfContracts2 Financing Receivable, Modifications, Number of Contracts Compensation and Employee Benefit Plans [Text Block] Loan Restructuring Modification [Axis] Wholesale Repurchase Agreements [Member] Information pertaining to wholesale repurchase agreements. Loan Restructuring Modification [Domain] 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. Impaired Financing Receivables [Table Text Block] 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. 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. Other assets 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. Other intangible assets Interest and Fees on Loans [Member] Primary financial statement caption encompassing interest and fees on loans. 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 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. Employee Stock Option [Member] 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] Deferred compensation liabilities Fair value portion of deferred compensation liabilities. Financing Receivables [Text Block] Deferred compensation assets Deferred compensation assets Fair value portion of deferred compensation assets. Commitments and Contingencies Disclosure [Text Block] 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. Premises and equipment, net Goodwill us-gaap_PaymentsForProceedsFromLoansAndLeases Proceeds from loans, net Bank Time Deposits [Member] 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. OREO [Member] Information pertaining to other real estate owned (OREO). fcbc_RestructuredLoansReserves Restructured Loans, Reserves Represents the amount of reserves for restructured loans. Long-term Debt, Type [Axis] Savings Deposits [Member] Information pertaining to savings deposits. Long-term Debt, Type [Domain] Reserve for unfunded commitments Represents the amount of reserve for unfunded credit commitments. FHLB advances us-gaap_FederalHomeLoanBankAdvancesWeightedAverageInterestRate Allowance for loan losses related to TDRs Represents the amount of allowance for loan losses. Derivative financial assets Derivative assets us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock Proceeds from FHLB stock, net Derivative Instrument [Axis] Decrease in other operating activities Derivative Contract [Domain] Investing activities Available-for-sale debt securities Debt securities available for sale Securities available for sale, fair value Debt securities held to maturity Securities held to maturity, amortized cost Total debt securities held to maturity, amortized cost Extinguishment of Debt, Type [Domain] Earnings per common share Earnings Per Share [Text Block] Discount range, impaired loans The measurement input for non-covered impaired loans. Payments to (reimbursements from) the FDIC The amount of cash payments received (made) on FDIC indemnification asset. 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. us-gaap_OtherThanTemporaryImpairmentLossDebtSecuritiesPortionRecognizedInEarnings Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings, Total Income tax expense Residential real estate loans in the foreclosure process(1) Securities held to maturity, due after five years but within ten years, amortized cost us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount Debt Instrument, Unused Borrowing Capacity, Amount Securities held to maturity, due after ten years, amortized cost Securities held to maturity, due within one year, amortized cost Securities held to maturity, due after one year but within five years, amortized cost Interest-bearing deposits in banks Securities held to maturity, due within one year, fair value Securities held to maturity, due after one year but within five years, fair value Securities held to maturity, due after five years but within ten years, fair value us-gaap_CashAndCashEquivalentsAtCarryingValue Total cash and cash equivalents Cash and cash equivalents at beginning of period Cash and cash equivalents at end of period Securities held to maturity, due after ten years, fair value 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 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 . 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 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. Allowance for loans collectively evaluated Interest Income Related to Troubled Debt Restructurings [Table Text Block] Tabular disclosure of interest income related to troubled debt restructurings. Amendment Flag FDIC Indemnification Asset Roll Forward [Table Text Block] us-gaap_ComprehensiveIncomeNetOfTax Total comprehensive income Use of Estimates, Policy [Policy Text Block] New Accounting Pronouncements, Policy [Policy Text Block] Credit Loss Status [Axis] Other Real Estate Owned [Table Text Block] Tabular disclosure of other real estate owned. Credit Loss Status [Domain] Reclassification, Policy [Policy Text Block] Financial Asset Acquired with Credit Deterioration [Member] Purchase of treasury shares, shares (in shares) us-gaap_GainLossOnSaleOfPropertyPlantEquipment Loss on sale of premises and equipment, net 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. Securities held to maturity, total fair value Current Fiscal Year End Date us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Recoveries Securities held to maturity, less than 12 months fair value Securities held to maturity, 12 months or longer fair value Basis of Accounting [Text Block] Interest receivable Document Fiscal Period Focus Document Fiscal Year Focus Consolidation, Policy [Policy Text Block] us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs Charge-offs us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet Net recoveries (charge-offs) Document Period End Date Document Type us-gaap_DividendsCommonStockCash Common dividends declared Document Information [Line Items] Document Information [Table] Entity Filer Category Entity Current Reporting Status Entity Voluntary Filers Entity Well-known Seasoned Issuer us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet Decrease in accrued interest receivable us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Securities held to maturity, 12 months or longer unrealized losses Federal Home Loan Bank Borrowings [Member] us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Securities held to maturity, less than 12 months unrealized losses Debt Securities, Held-to-maturity [Table Text Block] Equity-based compensation expense Statement of Comprehensive Income [Abstract] Entity Central Index Key Entity Registrant Name Liability Class [Axis] Fair Value by Liability Class [Domain] Entity [Domain] Legal Entity [Axis] Amortization of intangible assets Amortization of intangibles us-gaap_TreasuryStockValueAcquiredCostMethod Purchase of treasury shares FDIC indemnification asset Beginning balance Ending balance us-gaap_OtherRealEstate Total OREO us-gaap_TreasuryStockValue Treasury stock, at cost Covered OREO Other real estate owned, covered Other Real Estate, Covered, Ending Balance Non-covered OREO Other real estate owned, non-covered Entity Common Stock, Shares Outstanding (in shares) Depreciation and amortization of property, plant, and equipment Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] 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 Amortization of prior service cost Investments [Domain] us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses Amortization of losses Trading Symbol us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Net periodic cost Service cost Interest cost Occupancy expense Investment Type [Axis] 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) us-gaap_TableTextBlock Notes Tables us-gaap_GainLossOnSaleOfOtherAssets Loss on sale of other real estate owned us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity Line of Credit Facility, Maximum Borrowing Capacity Common stock options exercised Covered loans Covered Loans and Leases Receivable, Gross, Carrying Amount, Covered Loans held for investment, net of unearned income Securities held to maturity, fair value Total debt securities held to maturity, fair value us-gaap_LiabilitiesAndStockholdersEquity Total liabilities and stockholders' equity us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Reported Value Measurement [Member] Other operating expense Federal funds sold Interest-bearing Deposits [Member] Retained earnings Accumulated other comprehensive loss Demand Deposits [Member] Measurement Input, Discount Rate [Member] Debt Disclosure [Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] us-gaap_InterestExpense Total interest expense us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Derivative Instruments and Hedging Activities Disclosure [Text Block] Interest on long-term debt Interest on short-term borrowings Measurement Input Type [Axis] Measurement Input Type [Domain] Interest on deposits 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 Interest expense: Total Fair Value us-gaap_InterestAndDividendIncomeOperating Total interest income us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Amortization of premiums on investments, net Interest on deposits in banks FHLB and other borrowings Cash and cash equivalents us-gaap_SecuritiesLoanedOrSoldUnderAgreementsToRepurchaseFairValueDisclosure Securities sold under agreements to repurchase Interest on securities -- taxable Interest on securities -- tax-exempt Treasury stock (in shares) 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; 21,381,779 shares issued at March 31, 2018, and December 31, 2017; 4,534,327 and 4,383,553 shares in treasury at March 31, 2018, and December 31, 2017, respectively Adjustments to reconcile net income to net cash provided by operating activities Measurement Frequency [Axis] Interest and fees on loans Fair Value, Measurement Frequency [Domain] us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments Deposit Liabilities, Collateral Issued, Financial Instruments 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) Maturity Greater than 90 Days [Member] Range [Domain] Supplemental transactions -- noncash items Maximum [Member] Maturity Less than 30 Days [Member] Minimum [Member] Maturity 30 to 90 Days [Member] Weighted Average [Member] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] Product and Service [Axis] Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Product and Service [Domain] Range [Axis] Interest income: 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 Individual retirement accounts Cash paid for interest Preferred stock, no par value (in dollars per share) Money market accounts Savings deposits Preferred stock, authorized (in shares) Certificates of deposit Interest-bearing demand deposits Portion at Fair Value Measurement [Member] [Default] Preferred stock, par value (in dollars per share) Estimate of Fair Value Measurement [Member] Interest-bearing deposits: Total noninterest income Noninterest income Measurement Basis [Axis] Fair Value, Inputs, Level 3 [Member] Fair Value Hierarchy and NAV [Domain] Deposit Liabilities Disclosures [Text Block] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Noninterest income: Fair Value Hierarchy and NAV [Axis] Provision for loan losses Provision for loan losses Provision (Recovery) for loan losses charged to operations us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss Net interest income after provision for loan losses us-gaap_InterestIncomeExpenseNet Net interest income Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets [Table Text Block] Operating activities Revenue Recognition, Policy [Policy Text Block] Statement [Line Items] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] us-gaap_NumberOfOperatingSegments Number of Operating Segments 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 Schedule of Fair Value, Off-balance Sheet Risks [Table Text Block] Fair value loans Loans held for investment, net of allowance Deposit Account [Member] 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] Assets us-gaap_Liabilities Total liabilities us-gaap_NetCashProvidedByUsedInFinancingActivities Net cash provided by financing activities Other operating income Notional or contractual amount Derivative, Notional Amount us-gaap_NetCashProvidedByUsedInOperatingActivities Net cash provided by operating activities us-gaap_NetCashProvidedByUsedInInvestingActivities Net cash provided by investing activities us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease Net increase in cash and cash equivalents fcbc_DeferredLoanFees Deferred Loan Fees Represents deferred loan fees. Derivative financial liabilities Derivative liabilities Interest payable Others [Member] Information pertaining to other banks not separately disclosed. fcbc_PerformingStatusReturnedPeriod Performing Status Returned Period Represents the performing status return period. Impaired loans, related allowance Standby letters of credit and financial guarantees(1) Commitments to extend credit Impaired loans with no related allowance, interest income recognized Impaired loans with a related allowance, interest income recognized 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 Impaired loans with no related allowance, unpaid principal balance Impaired loans with a related allowance, unpaid principal balance us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance Total impaired loans, unpaid principal balance us-gaap_NoninterestExpense Total noninterest expense us-gaap_PaymentsForRepurchaseOfCommonStock Payments for repurchase of treasury stock Furniture and equipment expense FDIC premiums and assessments Retained Earnings [Member] Proceeds from stock options exercised Purchase of treasury shares, per share (in dollars per share) Treasury Stock [Member] fcbc_InterchangeIncomeExpenseNet Interchange Income (Expense), Net The net amount of interchange income (expense), net, from credit and debit card expenses. Allowance, excluding PCI Noninterest expense: Security settlements in process The amount of settlement that is in process, but not yet paid. Additional Paid-in Capital [Member] Total allowance 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] PCI allowance Equity Components [Axis] Equity Component [Domain] FHLB borrowings us-gaap_LongTermDebt Total Class of Financing Receivable, Type [Domain] Class of Financing Receivable, Type [Axis] Financing Receivable Portfolio Segment [Domain] Commercial Portfolio Segment [Member] Income before income taxes Income before income taxes Reclassification out of Accumulated Other Comprehensive Income [Member] Financing Receivable Portfolio Segment [Axis] fcbc_InterchangeIncome Interchange Income The amount of interchange income due to credit and debit card transactions during the period. Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Domain] Comprehensive Income (Loss) Note [Text Block] us-gaap_LineOfCredit Long-term Line of Credit, Total 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 Accounting Policies [Abstract] Cash dividends per common share (in dollars per share) Common dividends declared, per share (in dollars per share) Securities sold under agreements to repurchase Securities sold under agreements to repurchase Repurchase agreements us-gaap_BankOverdrafts Bank Overdrafts Receivable Type [Axis] Receivable [Domain] Income Statement Location [Axis] Deposits fair value Income Statement Location [Domain] Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] us-gaap_PaymentsToAcquireAvailableForSaleSecurities Payments to acquire securities available for sale Total dilutive effect of potential common shares (in shares) Interest, taxes, and other liabilities The aggregate amount of interest, taxes and other liabilities. Designated Par Value [Member] Information pertaining to preferred stock with a designated par value. 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Schedule of Available-for-sale Securities Reconciliation [Table Text Block] 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] Increase in interest-bearing deposits, net us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent Net unrealized (losses) gains on available-for-sale securities Securities available for sale, 12 months or longer, fair value Increase in noninterest-bearing deposits, net Securities available for sale, total fair value Deposit Liabilities, Type [Table Text Block] Fair Value Measurements, Nonrecurring [Table Text Block] Change in net unrealized (losses) gains on securities without other-than-temporary impairment us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax Net unrealized gains on employee benefit plans Financing activities Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Reclassification adjustment for amortization of prior service cost and net actuarial loss recognized in net income 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_SecurityOwnedAndPledgedAsCollateralFairValue Security Owned and Pledged as Collateral, Fair Value, Total fcbc_NumberOfSecuritiesInUnrealizedLossPosition Number of Securities in Unrealized Loss Position Represents the number of securities in unrealized loss position. Net actuarial (loss) gain 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. 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