Document And Entity Information Note To Financial Statement Details Textual Significant Accounting Policies Note 2 - Acquisitions and Divestitures Securities held to maturity, fair value Securities held to maturity, fair value Securities held to maturity Note 3 - Investment Securities Interest expense: Note 4 - Loans Note 5 - Credit Quality Securities held to maturity Securities held to maturity Securities held to maturity, amortized cost Note 6 - Allowance for Loan Losses Note 7 - FDIC Indemnification Asset Note 8 - Premises, Equipment, and Leases Note 9 - Goodwill and Other Intangible Assets Note 10 - Deposits Note 11 - Borrowings Cash dividends received from subsidiary bank us-gaap_AvailableForSaleSecuritiesPledgedAsCollateral Available-for-sale Securities Pledged as Collateral Note 12 - Derivative Instruments and Hedging Activities Note 13 - Employee Benefit Plans Note 14 - Other Operating Income and Expense Interest income Total interest income Note 15 - Income Taxes Note 16 - Accumulated Other Comprehensive Income Interest on deposits in banks Note 17 - Fair Value Note 18 - Earnings Per Share Securities available for sale Securities available for sale Securities available for sale 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) Note 2 - Acquisitions and Divestitures - Net Cash (Received) Paid in Acquisitions and Divestitures (Details) Note 3 - Investment Securities - Securities Available-for-sale (Details) Note 3 - Investment Securities - Securities by Contractual Maturity (Details) Note 3 - Investment Securities - Securities Held to Maturity (Details) Note 3 - Investment Securities - Amortized Cost and Fair Value of Municipal Securities by State, Including Gross Unrealized Gains and Losses (Details) Note 3 - Investment Securities - Available For Sale Securities in Continuous Unrealized Loss Position (Details) us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Note 3 - Investment Securities - Held to Maturity Securities in Continuous Unrealized Loss Position (Details) Note 3 - Investment Securities - Credit Losses Recognized in Earnings for Debt Securities Where Portion of Impairment Recognized in OCI (Details) Note 3 - Investment Securities - Gross Realized Gains and Losses from Sale of Securities (Details) Note 4 - Loans - Loans by Class (Details) Note 4 - Loans - Covered Loans by Class (Details) Note 4 - Loans - PCI loans (Details) Note 4 - Loans - Activity in Accretable Yield on PCI loans (Details) 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) Note 5 - Credit Quality - Average Annual Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) Note 5 - Credit Quality - Information on Impaired PCI Loan Pools (Details) Note 5 - Credit Quality - Nonaccrual Loans by Loan Class (Details) Note 5 - Credit Quality - Aging of Past Due Loans by Loan Class (Details) Interest on securities -- taxable 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 Trouble Debt Restructurings (Details) Interest on securities -- tax-exempt Note 5 - Credit Quality - Other Real Estate Owned (Details) 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) Note 8 - Premises, Equipment, and Leases - Components of Premises and Equipment (Details) Note 8 - Premises, Equipment, and Leases - Future Minimum Lease Payments to be Received Under Noncancelable Subleases (Details) Interest and fees on loans 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) Investment in subsidiaries Equity Method Investments Note 9 - Goodwill and Other Intangible Assets - Estimated Amortization Expense for Intangible Assets, by Year (Details) Note 10 - Deposits - Components of Deposits (Details) Note 10 - Deposits - Scheduled Maturities of Time Deposits (Details) Note 10 - Deposits - Scheduled Maturities of Certificates of Deposit of $250 Thousand or More (Details) Note 11 - Borrowings - Components of Borrowings (Details) Note 11- Borrowings - Contractual and Weighted Average Maturities of Long-term Borrowings (Details) Note 11 - Borrowings - Contractual Maturities of Repurchase Agreements (Details) Note 12 - Derivative Instruments and Hedging Activities - Notional or Contractual Amounts and Fair Values of Derivative Financial Instruments (Details) Note12 - Derivative Instruments and Hedging Activities - Effect of Derivative and Hedging Activity, on Consolidated Statements of Income (Details) 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) us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterest Portion of loss recognized in other comprehensive income 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) Use of Estimates, Policy [Policy Text Block] Note 14 - Other Operating Income and Expense - Components of Other Operating Income and Expense (Details) Reclassification of certain tax effects Prior Period Reclassification Adjustment Note 15 - Income Taxes - Components of Income Tax Provision (Details) Note 15 - Income Taxes - Reconciliation of Statutory Federal Tax Rate and Effective Tax Rate From Continuing Operations (Details) New Accounting Pronouncements, Policy [Policy Text Block] Note 15 - Income Taxes - Significant Components of Net Deferred Tax Asset (Details) Note 16 - Accumulated Other Comprehensive Income - Components of Accumulated Other Comprehensive Income, Net of Tax (Details) Note 16 - Accumulated Other Comprehensive Income - Reclassifications Out of Accumulated Other Comprehensive Income (Details) Reclassification, Policy [Policy Text Block] Note 17 - Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) 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) Interest income: Note 19 - Related Party Transactions - Changes in Loans With Related Parties (Details) 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) us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld Beginning balance Ending balance Note 22 - Parent Company Financial Information - Condensed Statements of Income (Details) Note 22 - Parent Company Financial Information - Condensed Statements of Cash Flows (Details) us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsReductionsSecuritiesSold Reduction for securities sold/realized losses 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. Additions for credit losses on securities not previously recognized Note 23 - Quarterly Financial Data (Unaudited) - Summary of Quarterly Earnings (Details) Allowance Excluding Purchased Credit Impaired Loans [Member] Information pertaining to the allowance excluding purchased credit impaired loans. Additions for credit losses on securities previously recognized Notes To Financial Statements Notes To Financial Statements [Abstract] Basis of Accounting [Text Block] Other than Temporary Impairment, Credit Losses Recognized in Earnings [Table 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 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. Waccamaw Serviced Home Equity Lines [Member] Information pertaining to Waccamaw serviced home equity lines. 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. 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. 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_DeferredCompensationArrangementWithIndividualRecordedLiability Deferred Compensation Arrangement with Individual, Recorded Liability us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense Deferred Compensation Arrangement with Individual, Compensation Expense Securities held to maturity, total fair value Unsecured Line of Credit [Member] Information pertaining to the unsecured line of credit. 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. us-gaap_TimeDepositMaturitiesAfterYearFive 2023 and thereafter us-gaap_TimeDepositMaturitiesYearFive 2022 Interest receivable us-gaap_TimeDepositMaturitiesYearTwo 2019 Weighted average maturity (in years) (Year) Represents the weighted average contractual maturity period. us-gaap_TimeDepositMaturitiesYearFour 2021 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. us-gaap_TimeDepositMaturitiesYearThree 2020 Time Deposit Maturities [Table Text Block] us-gaap_TimeDepositMaturitiesYearOne 2018 us-gaap_DepositLiabilitiesCollateralIssuedFinancialInstruments Deposit Liabilities, Collateral Issued, Financial Instruments Securities held to maturity, due after ten years, fair value Securities held to maturity, due after five years but within ten years, fair value Held-to-maturity, Fair value maturity: Securities held to maturity, due after one year but within five years, fair value Interest and Fees on Loans [Member] Primary financial statement caption encompassing interest and fees on loans. Securities held to maturity, due within one year, fair value Securities held to maturity, due after one year but within five years, amortized cost Directors' Plan [Member] Information pertaining to the Directors' Supplemental Retirement Plan (the Directors' Plan"). Securities held to maturity, due within one year, amortized cost Securities held to maturity, due after ten years, amortized cost Securities held to maturity, due after five years but within ten years, amortized cost Held-to-maturity, Amortized cost maturity: us-gaap_ImpairmentOfInvestments Net impairment losses recognized in earnings FDIC indemnification asset Beginning balance Ending balance Savings deposits us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss Securities held to maturity, 12 months or longer unrealized losses Individual retirement accounts Certificates of deposit Securities held to maturity, unrealized gains Interest-bearing demand deposits us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss Securities held to maturity, unrealized losses Money market accounts us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss Securities held to maturity, less than 12 months unrealized losses us-gaap_OtherRealEstate Total OREO Deferred compensation liabilities Fair value portion of deferred compensation liabilities. Non-covered OREO Other real estate owned, non-covered Interest-bearing deposits: Deferred compensation assets Deferred compensation assets Fair value portion of deferred compensation assets. us-gaap_TimeDepositsAtOrAboveFDICInsuranceLimit Time Deposits, at or Above FDIC Insurance Limit Total contractual maturities Impaired Loans [Member] Information pertaining to impaired loans. Covered OREO Other real estate owned, covered Other Real Estate, Covered Deposit Liabilities Disclosures [Text Block] us-gaap_DeferredTaxAssetsValuationAllowance Deferred Tax Assets, Valuation Allowance Unobservable Input Description of unobservable input used to measure fair value. Held-to-maturity Securities [Table Text Block] OREO [Member] Information pertaining to other real estate owned (OREO). us-gaap_LoansAndLeasesReceivableAllowance Allowance for loan losses Beginning balance Ending balance us-gaap_LoansAndLeasesReceivableNetReportedAmountCoveredAndNotCovered Loans held for investment, net us-gaap_DeferredTaxAssetsNet Total deferred tax assets Savings Deposits [Member] Information pertaining to savings deposits. Non-covered loans Non-covered Greenpoint Insurance Group [Member] Information pertaining to Greenpoint Insurance Group. 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] Virginia [Member] Information pertaining to Virginia. 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_DeferredIncomeTaxLiabilities Total deferred tax liabilities us-gaap_NoninterestIncome Total noninterest income us-gaap_DeferredTaxAssetsLiabilitiesNet Net deferred tax asset us-gaap_DeferredTaxAssetsOther Other us-gaap_BankOwnedLifeInsuranceIncome Bank owned life insurance Noninterest income: Net interest income after provision Net interest income after provision for loan losses Unrealized asset losses Intangible assets us-gaap_NumberOfReportableSegments Number of Reportable Segments Provision for loan losses Provision for loan losses Provision (Recovery) for loan losses charged to operations us-gaap_NumberOfOperatingSegments Number of Operating Segments Unrealized losses on available-for-sale securities Covered loans Covered Loans and Leases Receivable, Gross, Carrying Amount, Covered Other income (expense) Net interest income Net interest income Deferred loan fees Loans held for investment, net of unearned income Fair Value Measurement, Policy [Policy Text Block] Derivative Instruments, Gain (Loss) [Table Text Block] Service charges on deposits Derivative Instruments and Hedging Activities Disclosure [Text Block] Allowance for loan losses Federal funds sold us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements Interchange The amount of expense in period related to interchange. us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsEmployeeCompensation Deferred compensation assets Business Combinations Policy [Policy Text Block] 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. Earnings Per Share, Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] Reclassification from AOCI to Retained Earnings [Member] Represent information about reclassification from AOCI to retained earnings. Twelve Months Ended December 31, 2017 [Member] Represents information about period of twelve months ended December 31, 2017. Deferred tax assets Other Other operating income Total other operating income Community Banking [Member] Represents the community banking reporting unit. Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Acquisitions and dispositions, net Represents the net of goodwill acquired and disposed of during period. 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. 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. 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. us-gaap_LesseeLeasingArrangementsOperatingLeasesTermOfContract Lessee, Operating Lease, Term of Contract us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive 2023 and thereafter fcbc_DefinedContributionPlanMaximumEmployeeContributionAsPercentageOfBaseSalary Defined Contribution Plan, Maximum Employee Contribution as Percentage of Base Salary Represents the maximum percentage of base salary the employee contribution. Odd days interest deferral us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree 2020 Advertising Cost, Policy, Expensed Advertising Cost [Policy Text Block] fcbc_StoplossInsuranceLiabilityForAggregateClaims Stop-loss Insurance Liability for Aggregate Claims Amount of stop-loss insurance coverage for aggregate claims. us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo 2019 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive 2022 fcbc_StoplossInsuranceLiabilityForIndividualClaims Stop-loss Insurance Liability for Individual Claims Amount of stop-loss insurance coverage for individual claims. us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour 2021 Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] fcbc_DefinedBenefitPlanEmployerMatchingContributions Defined Benefit Plan, Employer Matching Contributions Amount of employer matching contributions to the plan. us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths 2018 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. 401 (k) Savings Plan [Member] Represents the company's 401K savings plan. Document Fiscal Period Focus us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1 Finite-Lived Intangible Assets, Remaining Amortization Period 2012 Omnibus Incentive Compensation Plan [Member] Represents the 2012 Omnibus Incentive compensation plan. Document Fiscal Year Focus First Four Anniversaries of Grant Date [Member] Represents the vesting percentage for the first four anniversaries of the grant date. Deferred tax liabilities Document Period End Date Service fees Fixed assets us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactions Total future minimum lease payments Document Type Document Information [Line Items] Document Information [Table] Entity Public Float us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinFourYears 2021 Entity Filer Category us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinThreeYears 2020 Entity Current Reporting Status Schedule of Finite-Lived Intangible Assets [Table Text Block] us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsThereafter 2023 and thereafter Entity Voluntary Filers us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinFiveYears 2022 Entity Well-known Seasoned Issuer fcbc_PercentageOfOperatingIncome Percentage of Operating Income Represents the percentage of operating income that other components cannot exceed. us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinTwoYears 2019 us-gaap_FutureMinimumSubleaseRentalsSaleLeasebackTransactionsWithinOneYear 2018 fcbc_OtherMiscellaneousIncome Other(1) Amounts of all other miscellaneous income not separately disclosed. us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit State 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. State Entity Central Index Key Entity Registrant Name us-gaap_DeferredFederalIncomeTaxExpenseBenefit Federal 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. Entity [Domain] Legal Entity [Axis] Federal us-gaap_CurrentIncomeTaxExpenseBenefit Total current tax expense Deferred tax expense (benefit): Current tax expense (benefit): Entity Common Stock, Shares Outstanding (in shares) 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. Insurance commissions fcbc_DeferredTaxLiabilitiesFederalDepositInsuranceCompanyTransaction FDIC indemnification asset Amount of deferred tax liability attributable to taxable temporary differences from Federal Deposit Insurance Company (FDIC) transactions. us-gaap_ReclassificationFromAociCurrentPeriodTax Income tax expense Purchase accounting Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from purchase accounting. Reclassification out of Accumulated Other Comprehensive Income [Axis] Other service charges and fees Reclassification out of Accumulated Other Comprehensive Income [Member] Wealth management Reclassification out of Accumulated Other Comprehensive Income [Domain] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Trading Symbol Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Comprehensive Income (Loss) Note [Text Block] 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. 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. fcbc_TierOneCapitalSecuritiesPhaseOutPeriod Tier One Capital Securities Phase Out Period Represents the phase out period for Tier 1 capital securities. Goodwill and Intangible Assets, Policy [Policy Text Block] 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. FDIC premiums and assessments Noninterest expense Total noninterest expense Furniture and equipment expense us-gaap_PropertyPlantAndEquipmentUsefulLife Property, Plant and Equipment, Useful Life Condensed Financial Information of Parent Company Only Disclosure [Text Block] Assets Noninterest expense: Furniture and Fixtures [Member] Net cash used in financing activities Net cash used in financing activities Building and Building Improvements [Member] Net cash provided by investing activities Net cash provided by (used in) investing activities Net cash provided by operating activities Net cash provided by operating activities Net (decrease) increase in cash and cash equivalents Net increase (decrease) in cash and cash equivalents Land Improvements [Member] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Axis] Income before income taxes Income before income taxes Income before income taxes Property, Plant and Equipment, Policy [Policy Text Block] Net change in other financing activities Business Acquisition, Acquiree [Domain] Business Acquisition [Axis] Excess tax benefit from equity-based compensation us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock Payments of preferred dividends us-gaap_PaymentsOfDividendsCommonStock Payments of common dividends us-gaap_PaymentsForRepurchaseOfPreferredStockAndPreferenceStock Redemption of preferred stock Derivatives, Policy [Policy Text Block] Repurchase Agreements, Collateral, Policy [Policy Text Block] us-gaap_PaymentsForRepurchaseOfCommonStock Payments for repurchase of treasury stock Reclassification of certain tax effects fcbc_ReclassificationFromAociForStrandedTaxCurrentPeriodNetOfTaxAttributableToParent Amount after tax of reclassification adjustments for stranded tax of other comprehensive income (loss) attributable to parent. Proceeds from stock options exercised Common dividends declared, per share (in dollars per share) Proceeds from issuance of common stock Marketable Securities, Policy [Policy Text Block] 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 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 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 Asset Class [Axis] Asset Class [Domain] Residential Real Estate [Member] Weighted average diluted shares outstanding (in shares) Diluted (in shares) Weighted average common shares outstanding, diluted (in shares) Antidilutive potential common shares (in shares) Equity Securities [Member] Total dilutive effect of potential common shares (in shares) Collateral [Domain] Collateral [Axis] us-gaap_RepaymentsOfOtherDebt Repayments of other debt us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities Class of Financing Receivable, Type [Domain] Diluted (in dollars per share) Diluted earnings per common share (in dollars per share) Class of Financing Receivable, Type [Axis] Repayments of FHLB and other borrowings, net us-gaap_RepaymentsOfLongTermDebt Repayments of long-term debt us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther Other liabilities Financing Receivable Portfolio Segment [Domain] Financing Receivable Portfolio Segment [Axis] Weighted average common shares outstanding, basic (in shares) Basic (in shares) Commercial Portfolio Segment [Member] us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable Deposits Basic (in dollars per share) Basic earnings per common share (in dollars per share) us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment Premises and equipment Preferred dividends declared, per share (in dollars per share) us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets Other assets CONNECTICUT Schedule of Financing Receivables, Non Accrual Status [Table Text Block] IOWA us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables Loans Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] Fully Phased-In [Member] Represents the fully phased in minimum Basel III requirements. us-gaap_ProceedsFromIssuanceOfSubordinatedLongTermDebt Proceeds from Issuance of Subordinated Long-term Debt Fair value of assets and liabilities acquired: Finance, Loan and Lease Receivables, Held-for-investment, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Non-cash purchase price Basis of Accounting, Policy [Policy Text Block] NEW JERSEY NEW YORK OHIO Accounting Policies [Abstract] Parent Company [Member] Statement of Financial Position [Abstract] Consolidated Entities [Domain] Consolidated Entities [Axis] TEXAS WISCONSIN Condensed Cash Flow Statement [Table Text Block] Statement of Cash Flows [Abstract] Condensed Income Statement [Table Text Block] Statement of Stockholders' Equity [Abstract] Condensed Balance Sheet [Table Text Block] Receivable [Domain] Receivable Type [Axis] Quarterly Financial Information [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Investments Classified by Contractual Maturity Date [Table Text Block] Realized Gain (Loss) on Investments [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) [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] (Repayments of) proceeds from 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] us-gaap_DueToOtherRelatedPartiesCurrentAndNoncurrent Due to Other Related Parties 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. Other items, net us-gaap_EffectiveIncomeTaxRateContinuingOperations Income tax at the effective tax rate us-gaap_DividendsPayableCurrentAndNoncurrent Dividends Payable Other Intangible Assets [Member] Deferred tax revaluation us-gaap_EffectiveIncomeTaxRateReconciliationTaxExemptIncome Tax-exempt interest income Credit Facility [Domain] Series A Preferred Stock [Member] Increase (decrease) in noninterest-bearing deposits, net Increase (decrease) in interest-bearing deposits, net Credit Facility [Axis] 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. fcbc_PaymentsForProceedsFromDivestitureOfBusinessesNetOfCashDivested Net cash received in divestitures The cash outflow or inflow associated with the divestiture of businesses, net of cash divested. Financing activities Book value of assets sold Amount classified as assets sold (acquired) attributable to disposal group held for sale or disposed of. us-gaap_PaymentsForProceedsFromOtherInvestingActivities Net change in other investing activities Book value of liabilities sold Amount classified as liabilities sold (incurred) attributable to disposal group held for sale or disposed of Class of Stock [Domain] Nondeductible goodwill Class of Stock [Axis] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Dividends in excess of undistributed net income of subsidiaries Core Deposits [Member] Allowance, excluding PCI Total allowance Finite-Lived Intangible Assets, Major Class Name [Domain] Unlikely to be Collected Financing Receivable [Member] us-gaap_PaymentsForProceedsFromBusinessesAndInterestInAffiliates Cash proceeds from (paid in) mergers, acquisitions, and divestitures, net (See Note 2) Net cash (received) paid in acquisitions and divestitures PCI allowance Special Mention [Member] State income tax, net of federal benefit Finite-Lived Intangible Assets by Major Class [Axis] Doubtful [Member] Substandard [Member] Proceeds from divestitures Proceeds from Divestiture of Businesses Divestitures Other items, net, amount Federal income tax at the statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent us-gaap_CashDivestedFromDeconsolidation Cash sold Deferred tax revaluation, amount Designated as Hedging Instrument [Member] Loans to affiliates us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired Net cash paid in acquisitions Hedging Designation [Domain] Hedging Designation [Axis] us-gaap_LoansAndLeasesReceivableRelatedParties Beginning balance Ending balance us-gaap_GoodwillAndIntangibleAssetImpairment Goodwill and Intangible Asset Impairment Schedule of Maturities of Long-term Debt [Table Text Block] Cash acquired Schedule of Debt [Table Text Block] us-gaap_IncomeTaxReconciliationTaxExemptIncome Tax-exempt interest income, amount us-gaap_PaymentsToAcquireBusinessesGross Payments to Acquire Businesses, Gross Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Share-based Compensation, Stock Options, Activity [Table Text Block] Cash consideration paid Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Nondeductible goodwill, amount Schedule of Business Acquisitions, by Acquisition [Table Text Block] Business Combination Disclosure [Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Net Funded Status [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] State income tax, net of federal benefit, amount 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. Federal income tax at the statutory rate, amount 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. Reclassifications Reflects the amount of reclassification made to related parties in the form of loan and lease receivables. Other operating expense: Other operating income: Income Tax Disclosure [Text Block] Proceeds from maturities and calls of securities held to maturity Proceeds from maturities, prepayments, and calls of securities available for sale Proceeds from sale of securities available for sale Acquisitions in 2015 [Member] Represents all acquisitions during the year, 2015. Acquisitions in 2016 [Member] Represents all acquisitions during the year, 2016. fcbc_NumberOfOfficesSold Number of Offices Sold Represents the number of offices sold. Supplemental Employee Retirement Plan [Member] Proceeds from sale of other real estate Retirement Plan Type [Axis] Pass [Member] Retirement Plan Type [Domain] Long-term Debt, Type [Axis] Increase in accumulated other comprehensive income Represents the increase in accumulated other comprehensive income in noncash investing or financing activities. Long-term Debt, Type [Domain] Internal Credit Assessment [Domain] (Dividends in excess of) equity in 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. Internal Credit Assessment [Axis] us-gaap_PaymentsToAcquireHeldToMaturitySecurities Payments to acquire securities held to maturity us-gaap_PaymentsToAcquireAvailableForSaleSecurities Payments to acquire securities available for sale 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. Convertible preferred stock (in shares) Undesignated Par Value [Member] Information pertaining to preferred stock with an undesignated par value. Dilutive effect of potential common shares (in shares) Weighted average shares outstanding Extinguishment of Debt, Type [Domain] us-gaap_PaymentsForProceedsFromProductiveAssets Payments to acquire property, plant, and equipment, net Schedule of Goodwill [Table Text Block] Net income available to common shareholders Net income available to common shareholders Extinguishment of Debt [Axis] Goodwill and Intangible Assets Disclosure [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). 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. 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. us-gaap_DebtInstrumentTerm Debt Instrument, Term Divestiture of Bank Branches to First Bank [Member] Information pertaining to the divestiture of bank branches to First Bank. us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount Debt Instrument, Unused Borrowing Capacity, Amount North Carolina [Member] Information pertaining to the geographical location of North Carolina. us-gaap_RelatedPartyDepositLiabilities Related Party Deposit Liabilities 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. Southwestern Virginia [Member] Information pertaining to the geographical location of southwestern Virginia. Restricted Stock [Member] us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty Related Party Transaction, Expenses from Transactions with Related Party fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLoansReceivable Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Loans Receivable Amount of loans receivable acquired, at the acquisition date. TDRs Financing Receivable, Modifications, Recorded Investment Antidilutive Securities, Name [Domain] Employee Stock Option [Member] 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. fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeposits Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deposits Amount of deposits assumed at the acquisition date. Transfer of loans to other real estate Schedule of Related Party Transactions [Table Text Block] Recorded investment, Subsequent Default Antidilutive Securities [Axis] fcbc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssetsIncludingGoodwill Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets including Goodwill Amount of assets including goodwill acquired at the acquisition date. Total contracts, Subsequent Default Total contracts Related Party Transactions Disclosure [Text Block] Post-modification recorded investment Pre-modification recorded investment 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] 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] Troubled Debt Restructurings on Financing Receivables [Table Text Block] Subordinated debt, rate us-gaap_DebtWeightedAverageInterestRate us-gaap_DebtInstrumentBasisSpreadOnVariableRate1 Debt Instrument, Basis Spread on Variable Rate Financing Receivable Credit Quality Indicators [Table Text Block] Current loans 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 us-gaap_PaymentsForProceedsFromLoansAndLeases Repayments of (originations of) loans, net Financing Receivables, Equal to Greater than 90 Days Past Due [Member] Financing Receivables, 60 to 89 Days Past Due [Member] London Interbank Offered Rate (LIBOR) [Member] Financing Receivables, Period Past Due [Domain] Financing Receivables, Period Past Due [Axis] Financing Receivables, 30 to 59 Days Past Due [Member] Financing Receivables [Text Block] Variable Rate [Domain] Variable Rate [Axis] Past Due Financing Receivables [Table Text Block] us-gaap_PaymentsForProceedsFromFederalHomeLoanBankStock Redemptions of FHLB stock, net Decrease in other operating activities FHLB advances us-gaap_FederalHomeLoanBankAdvancesWeightedAverageInterestRate Investing activities Reported Value Measurement [Member] Interest-bearing Deposits [Member] Demand Deposits [Member] us-gaap_ComprehensiveIncomeNetOfTax Total comprehensive income Quarterly Financial Information [Text Block] 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) fcbc_NumberOfLoanPortfolioSegments Number of Loan Portfolio Segments Represents the number of loan portfolio segments. Preferred stock, outstanding (in shares) 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. 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. 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. us-gaap_DividendsCommonStockCash Common dividends declared us-gaap_DividendsPreferredStockCash Preferred dividends declared 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). Debt Disclosure [Text Block] Equity-based compensation expense Discount range us-gaap_TreasuryStockValueAcquiredCostMethod Purchase of treasury shares us-gaap_ConversionOfStockSharesConverted1 Conversion of Stock, Shares Converted us-gaap_TreasuryStockValue Treasury stock Redemption of preferred stock, shares (in shares) Stock Redeemed or Called During Period, Shares us-gaap_StockRedeemedOrCalledDuringPeriodValue Stock Redeemed or Called During Period, Value Redemption of preferred stock us-gaap_StockRepurchasedDuringPeriodShares Stock Repurchased During Period, Shares us-gaap_StockRepurchasedDuringPeriodValue Stock Repurchased During Period, Value Federal Home Loan Bank Borrowings [Member] Preferred stock converted to common stock, shares (in shares) Fair Value by Liability Class [Domain] Junior Subordinated Debt [Member] Liability Class [Axis] Preferred stock converted to common stock 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. 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] Pre-tax compensation expense 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. Restricted stock awards, shares (in shares) Loans individually evaluated for impairment Common stock options exercised, shares (in shares) Exercised (in shares) Peoples Bank of Virginia [Member] Information pertaining to Peoples Bank of Virginia. Loans collectively evaluated for impairment Financing Receivable, Collectively Evaluated for Impairment Waccamaw Bank [Member] Information pertaining to Waccamaw Bank. Common stock options exercised Supplemental transactions – noncash items 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. Allowance for loans collectively evaluated Other Receivables [Member] Information pertaining to other receivables. Allowance for loans individually evaluated Decrease in estimated losses on covered loans Receivables Acquired with Deteriorated Credit Quality [Domain] 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] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod Canceled (in shares) Granted (in shares) Allowance for Credit Losses on Financing Receivables [Table Text Block] Stock options granted (in shares) Recoveries Allowance for loan losses related to PCI loan pools fcbc_PercentageOfLoanLossCoveredByFDIC Percentage of Loan Loss Covered by FDIC Represents the percentage of loan covered by the FDIC. Non-covered Loans [Member] Information pertaining to non-covered loans. Covered Loans [Member] Information pertaining to covered loans. us-gaap_AllowanceForLoanAndLeaseLossesWriteoffsNet Net recoveries (charge-offs) Total liabilities and stockholders' equity Total liabilities and stockholders' equity fcbc_RestructuredLoansReserves Restructured Loans, Reserves Represents the amount of reserves for restructured loans. Retained earnings us-gaap_AllowanceForLoanAndLeaseLossesWriteOffs Charge-offs Accumulated other comprehensive loss us-gaap_PaymentsForOriginationOfMortgageLoansHeldForSale Originations of mortgage loans Proceeds from sale of mortgage loans 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. 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. Non-marketable Equity Investments Policy [Policy Text Block] Disclosure of accounting policy for nonmarketable securities. Other Investments [Policy Text Block] Disclosure of accounting policy for all other investments not included in marketable and nonmarketable securities. fcbc_LoanDelinquentPeriod Loan Delinquent Period Period of time loans are considered delinquent and past due. fcbc_LoanPaymentsDelinquencyPeriodBeyondWhichLoanIsConsideredNonAccrual Loan Payments Delinquency Period Beyond which Loan is Considered Non Accrual Period of time in delinquency after loan is considered impaired. fcbc_NumberOfPeriodUsedToCalculateAllowanceForLoans Number Of Period Used To Calculate Allowance For Loans Represents the number of days used to calculate loan allowance. fcbc_MinimumPrincipalBalanceOfLoansSubjectToReserveBasedOnCollateralOrNetPresentValueMethod Minimum Principal Balance of Loans Subject to Reserve Based on Collateral or Net Present Value Method Minimum amount of principal balance of loans subject to reserve, based on collateral and net present value. fcbc_MaximumPrincipalBalanceOfLoansSubjectToReserveBasedOnHistoricalLossRate Maximum Principal Balance of Loans Subject to Reserve Based on Historical Loss Rate Maximum amount of principal balance of loans subject to reserve, based on historical loss rates. 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. Unsecured Loan [Member] Represents unsecured loans. Insurance Service Segment [Member] Represents the insurance service disposal group. fcbc_NumberOfBusinessesSold Number Of Businesses Sold Represents the number of businesses sold. us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost Net periodic cost 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. Interest cost Service cost fcbc_EarnOutPaymentForAcquisitionOfBusiness Earn Out Payment For Acquisition Of Business Amount of earn-out payment from acquisition of business. Amortization of prior service cost 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. us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses Amortization of losses 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. Fair Value, Measurements, Nonrecurring [Member] Fair Value, Measurements, Recurring [Member] Valuation Technique Fair Value, Measurement Frequency [Domain] 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. Measurement Frequency [Axis] Property, Plant and Equipment [Table Text Block] Property, Plant and Equipment Disclosure [Text Block] 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. us-gaap_OperatingLeasesRentExpenseNet Operating Leases, Rent Expense, Net Trouble Debt Restructuring Accrual Status [Table Text Block] Tabular disclosure of accrual status related to trouble debt restructuring . Income before equity in undistributed net income of subsidiaries 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. us-gaap_DeferredIncomeTaxExpenseBenefit Total deferred tax expense (benefit) Impaired PCI loan pools Represents the number of impaired loans. Troubled Debt Restructurings [Member] Information pertaining to trouble debt restructurings. Treasury stock (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. FHLB and other borrowings 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. Common stock, $1 par value; 50,000,000 shares authorized; 21,381,779 shares issued at December 31, 2017 and 2016; 4,383,553 and 4,387,571 shares in treasury at December 31, 2017 and 2016, respectively Common stock 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, authorized (in shares) Common stock, issued (in shares) fcbc_IndemnificationPercentage Indemnification Percentage Represents the percentage of indemnification. us-gaap_StockOptionPlanExpense Issuance of treasury stock to 401(k) plan Common stock, par value (in dollars per share) us-gaap_ShareBasedCompensation Equity-based compensation expense 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_RestrictedStockExpense Restricted stock awards Fair Value, Measurement Inputs, Disclosure [Text Block] us-gaap_CommonStockSharesHeldInEmployeeTrustShares Common Stock, Shares Held in Employee Trust, Shares 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 us-gaap_AccretionAmortizationOfDiscountsAndPremiumsInvestments Amortization of premiums on investments, net Other comprehensive income Other comprehensive income (loss), net Preferred stock, no par value (in dollars per share) us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1 Income tax expense Preferred stock, authorized (in shares) Preferred stock, par value (in dollars per share) us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent Other comprehensive income, before tax Estimate of Fair Value Measurement [Member] us-gaap_ConvertiblePreferredStockSharesIssuedUponConversion Convertible Preferred Stock, Shares Issued upon Conversion Measurement Basis [Axis] Portion at Fair Value Measurement [Member] Purchase of treasury shares, per share (in dollars per share) Adjustments to reconcile net income to net cash provided by operating activities us-gaap_OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentBeforeTaxPortionAttributableToParent Net unrealized gains on available-for-sale securities Total Fair Value Reclassification adjustment for other-than-temporary impairment losses recognized in net income us-gaap_PreferredStockDividendRatePercentage Preferred Stock, Dividend Rate, Percentage Schedule of Other Operating Cost and Expense, by Component [Table Text Block] Change in net unrealized gains on securities without other-than-temporary impairment us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesBeforeTax Reclassification adjustment for net loss (gain) 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 (losses) on employee benefit plans Additional paid-in capital Net actuarial loss Cash paid for interest us-gaap_OtherComprehensiveIncomeDefinedBenefitPlanNetPriorServiceCostCreditArisingDuringPeriodBeforeTax Plan change Cash and cash equivalents Stockholders' equity Commitments to extend credit Standby letters of credit and financial guarantees(1) Other Income and Other Expense Disclosure [Text Block] Other comprehensive income, before tax Total stockholders' equity Total stockholders' equity Balance Balance US Treasury Securities [Member] Total liabilities Total liabilities US Government Agencies Debt Securities [Member] Other liabilities us-gaap_LiabilitiesOfDisposalGroupIncludingDiscontinuedOperation Disposal Group, Including Discontinued Operation, Liabilities Maturity Greater than 90 Days [Member] Deposits fair value Operating activities Maturity 30 to 90 Days [Member] Maturity Less than 30 Days [Member] Repurchase Agreements and Similar Transactions, Maturity Periods [Axis] us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability Total off-balance sheet risk Repurchase Agreements and Similar Transactions, Maturity Periods [Domain] Statement [Line Items] Schedule of Fair Value, Off-balance Sheet Risks [Table Text Block] Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Derivative financial liabilities Derivative liabilities Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member] us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Fair value loans Loans held for investment, net of allowance Interest payable AOCI Attributable to Parent [Member] Fair Value, by Balance Sheet Grouping [Table Text Block] us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent Reclassified from AOCI Other comprehensive income (loss) before reclassifications Interest Rate Swap [Member] us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax Income before income taxes us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax Net income Type of Adoption [Domain] Adjustments for New Accounting Pronouncements [Axis] us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear 2018 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour 2021 us-gaap_LongTermDebt Total Other borrowings us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree 2020 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive 2023 and thereafter us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive 2022 Financial Instruments [Domain] FHLB borrowings us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo 2019 Financial Instrument [Axis] 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] Fair Value Hierarchy [Domain] Fair Value, Hierarchy [Axis] Subordinated debt Subordinated debt Subordinated Debt Equity Component [Domain] Preferred Stock [Member] Common Stock [Member] Report Date [Axis] Equity Components [Axis] Financial Statement Filing Date [Domain] Allowance for Credit Losses [Text Block] 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. 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. Securities sold under agreements to repurchase Securities sold under agreements to repurchase Repurchase agreements us-gaap_BankOverdrafts Bank Overdrafts 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. 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Income before income taxes and equity in undistributed net income of subsidiaries Others [Member] Information pertaining to other banks not separately disclosed. us-gaap_IncomeLossFromEquityMethodInvestments Equity in undistributed net income of subsidiaries Income tax expense Total income tax expense Income tax expense fcbc_PerformingStatusReturnedPeriod Performing Status Returned Period Represents the performing status return period. 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period (in shares) Options outstanding at end of period (in shares) us-gaap_FDICIndemnificationAssetCashPaymentsReceived Reimbursements from the FDIC Depreciation and amortization of property, plant, and equipment Depreciation, Nonproduction FDIC Indemnification Asset Roll Forward [Table Text Block] New loans and advances Liabilities Professional fees Advertising and public relations us-gaap_LoansAndLeasesReceivableRelatedPartiesProceeds Loan repayments us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Office supplies Total assets Total assets us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeePercent Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Occupancy expense us-gaap_AssetsOfDisposalGroupIncludingDiscontinuedOperation Disposal Group, Including Discontinued Operation, Assets Loans, Notes, Trade and Other Receivables Disclosure [Text Block] us-gaap_GainLossOnSaleOfOtherAssets Loss on sale of other real estate us-gaap_DisposalGroupIncludingDiscontinuedOperationAccountsNotesAndLoansReceivableNet Disposal Group, Including Discontinued Operation, Accounts, Notes and Loans Receivable, Net us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Tier 1 Leverage, actual ratio Vesting [Domain] Tier 1 Leverage, to be well capitalized ratio Tier 1 Leverage, required ratio Plan Name [Axis] Total risk-based capital, to be well capitalized ratio Total risk-based capital, required ratio Vesting [Axis] Common equity Tier 1, actual ratio Plan Name [Domain] Other assets 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Comprehensive Income [Abstract] Common equity Tier 1 ratio, actual amount Tier 1 risk-based capital ratio, actual amount Nontaxable Municipal Bonds [Member] Tier 1 risk-based capital to be well capitalized, amount Tier 1 risk-based capital ratio, required amount us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour 2021 Interest expense Total interest expense us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree 2020 us-gaap_VariableInterestDifferenceBetweenCarryingAmountAndMaximumExposure Variable Interest Entity, Nonconsolidated, Comparison of Carrying Amount of Assets and Liabilities to Maximum Loss Exposure us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter 2023 through 2027 us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive 2022 Investments [Domain] Investment Type [Axis] us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo 2019 Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths 2018 FHLB debt prepayment fees Regulatory Capital Requirements under Banking Regulations [Text Block] Goodwill Balance January 1 Balance December 31 Premises and equipment, net Total premises and equipment, net us-gaap_OtherRevenueExpenseFromRealEstateOperations OREO expense and net loss us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Accumulated depreciation and amortization us-gaap_PropertyPlantAndEquipmentGross Total premises and equipment Interest on long-term debt Land Buildings and leasehold improvements Equipment Interest on short-term borrowings Assumed discount rate us-gaap_TableTextBlock Notes Tables Interest on deposits Derivative assets us-gaap_InvestmentOwnedAtCost Investment Owned, at Cost