<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.0.8</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>671</ContextCount>
  <ElementCount>418</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>131</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>101 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DocumentandEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>103 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfFinancialPositionUnclassified-DepositBasedOperations</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>104 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfFinancialPositionUnclassified-DepositBasedOperationsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>105 - Statement - Condensed Consolidated Statements Of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfIncomeInterestBasedRevenue</Role>
      <ShortName>Condensed Consolidated Statements Of Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>106 - Statement - Condensed Consolidated Statements Of Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfOtherComprehensiveIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Comprehensive Income (Loss)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>107 - Statement - Condensed Consolidated Statements Of Changes In Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Changes In Stockholders' Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>108 - Statement - Condensed Consolidated Statements Of Changes In Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfShareholdersEquityAndOtherComprehensiveIncomeParenthetical</Role>
      <ShortName>Condensed Consolidated Statements Of Changes In Stockholders' Equity (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>109 - Statement - Condensed Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/StatementOfCashFlowsIndirectDepositBasedOperations</Role>
      <ShortName>Condensed Consolidated Statements Of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>110 - Disclosure - General</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock</Role>
      <ShortName>General</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>111 - Disclosure - Investment Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsInvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlock</Role>
      <ShortName>Investment Securities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>112 - Disclosure - Loans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsLoansNotesTradeAndOtherReceivablesDisclosureTextBlock</Role>
      <ShortName>Loans</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>113 - Disclosure - Credit Quality</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFinancingReceivablesTextBlock</Role>
      <ShortName>Credit Quality</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>114 - Disclosure - Allowance for Loan Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsAllowanceForCreditLossesTextBlock</Role>
      <ShortName>Allowance for Loan Losses</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>115 - Disclosure - FDIC Indemnification Asset</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFdicLossShareAgreementReceivableTextBlock</Role>
      <ShortName>FDIC Indemnification Asset</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>116 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDepositLiabilitiesDisclosuresTextBlock</Role>
      <ShortName>Deposits</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>117 - Disclosure - Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlock</Role>
      <ShortName>Borrowings</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>118 - Disclosure - Derivative Instruments and Hedging Activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlock</Role>
      <ShortName>Derivative Instruments and Hedging Activities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>119 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsCompensationAndEmployeeBenefitPlansTextBlock</Role>
      <ShortName>Employee Benefit Plans</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>120 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlock</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>121 - Disclosure - Fair Value</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFairValueMeasurementInputsDisclosureTextBlock</Role>
      <ShortName>Fair Value</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>122 - Disclosure - Litigation, Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlock</Role>
      <ShortName>Litigation, Commitments and Contingencies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>123 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsSubsequentEventsTextBlock</Role>
      <ShortName>Subsequent Events</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>124 - Disclosure - General (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlockPolicies</Role>
      <ShortName>General (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>125 - Disclosure - General (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlockTables</Role>
      <ShortName>General (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>126 - Disclosure - Investment Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsInvestmentsInDebtAndMarketableEquitySecuritiesAndCertainTradingAssetsDisclosureTextBlockTables</Role>
      <ShortName>Investment Securities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>127 - Disclosure - Loans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsLoansNotesTradeAndOtherReceivablesDisclosureTextBlockTables</Role>
      <ShortName>Loans (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>128 - Disclosure - Credit Quality (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFinancingReceivablesTextBlockTables</Role>
      <ShortName>Credit Quality (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>129 - Disclosure - Allowance for Loan Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsAllowanceForCreditLossesTextBlockTables</Role>
      <ShortName>Allowance for Loan Losses (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>130 - Disclosure - FDIC Indemnification Asset (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFdicLossShareAgreementReceivableTextBlockTables</Role>
      <ShortName>FDIC Indemnification Asset (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>131 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDepositLiabilitiesDisclosuresTextBlockTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>132 - Disclosure - Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDebtDisclosureTextBlockTables</Role>
      <ShortName>Borrowings (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>133 - Disclosure - Derivative Instruments and Hedging Activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsDerivativeInstrumentsAndHedgingActivitiesDisclosureTextBlockTables</Role>
      <ShortName>Derivative Instruments and Hedging Activities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>134 - Disclosure - Employee Benefit Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsCompensationAndEmployeeBenefitPlansTextBlockTables</Role>
      <ShortName>Employee Benefit Plans (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>135 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsComprehensiveIncomeNoteTextBlockTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>136 - Disclosure - Fair Value (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsFairValueMeasurementInputsDisclosureTextBlockTables</Role>
      <ShortName>Fair Value (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>137 - Disclosure - Litigation, Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/NotesToFinancialStatementsCommitmentsAndContingenciesDisclosureTextBlockTables</Role>
      <ShortName>Litigation, Commitments and Contingencies (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>138 - Disclosure - General - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureGeneralAdditionalInformation</Role>
      <ShortName>General - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>139 - Disclosure - Calculation for Basic and Diluted Earnings per Common Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCalculationForBasicAndDilutedEarningsPerCommonShare</Role>
      <ShortName>Calculation for Basic and Diluted Earnings per Common Share (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>140 - Disclosure - Amortized Cost and Fair Value of Available-For-Sale Securities, Including Gross Unrealized Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAmortizedCostAndFairValueOfAvailableForSaleSecuritiesIncludingGrossUnrealizedGainsAndLosses</Role>
      <ShortName>Amortized Cost and Fair Value of Available-For-Sale Securities, Including Gross Unrealized Gains and Losses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>141 - Disclosure - Amortized Cost and Fair Value of Held-to-Maturity Securities, Including Gross Unrealized Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAmortizedCostAndFairValueOfHeldtoMaturitySecuritiesIncludingGrossUnrealizedGainsAndLosses</Role>
      <ShortName>Amortized Cost and Fair Value of Held-to-Maturity Securities, Including Gross Unrealized Gains and Losses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>142 - Disclosure - Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAmortizedCostAndFairValueOfAvailableforSaleAndHeldtoMaturitySecurities</Role>
      <ShortName>Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Securities (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>143 - Disclosure - Available-For-Sale Securities in Continuous Unrealized Loss Position (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAvailableForSaleSecuritiesInContinuousUnrealizedLossPosition</Role>
      <ShortName>Available-For-Sale Securities in Continuous Unrealized Loss Position (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>144 - Disclosure - Investment Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureInvestmentSecuritiesAdditionalInformation</Role>
      <ShortName>Investment Securities - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>145 - Disclosure - Held to Maturity Securities in Continuous Unrealized Loss Position (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureHeldToMaturitySecuritiesInContinuousUnrealizedLossPosition</Role>
      <ShortName>Held to Maturity Securities in Continuous Unrealized Loss Position (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>146 - Disclosure - Net Loss or Gain from Sale of Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureNetLossOrGainFromSaleOfSecurities</Role>
      <ShortName>Net Loss or Gain from Sale of Securities (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>147 - Disclosure - Credit Losses Recognized in Earnings for Debt Securities Where Portion of OTTI Recognized in OCI (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCreditLossesRecognizedInEarningsForDebtSecuritiesWherePortionOfOTTIRecognizedInOCI</Role>
      <ShortName>Credit Losses Recognized in Earnings for Debt Securities Where Portion of OTTI Recognized in OCI (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>148 - Disclosure - Loans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLoansAdditionalInformation</Role>
      <ShortName>Loans - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>149 - Disclosure - Summary of Loans, Net of Unearned Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureSummaryOfLoansNetOfUnearnedIncome</Role>
      <ShortName>Summary of Loans, Net of Unearned Income (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>150 - Disclosure - Components of Covered Loan Portfolio, Disaggregated by Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureComponentsOfCoveredLoanPortfolioDisaggregatedByClass</Role>
      <ShortName>Components of Covered Loan Portfolio, Disaggregated by Class (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>151 - Disclosure - Carrying and Contractual Unpaid Principal Balance of PCI loans, by Acquisition (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCarryingAndContractualUnpaidPrincipalBalanceOfPCILoansByAcquisition</Role>
      <ShortName>Carrying and Contractual Unpaid Principal Balance of PCI loans, by Acquisition (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>152 - Disclosure - Activity in Accretable Yield Related to PCI loans, by Acquisition (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureActivityInAccretableYieldRelatedToPCILoansByAcquisition</Role>
      <ShortName>Activity in Accretable Yield Related to PCI loans, by Acquisition (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>153 - Disclosure - Recorded Investment and Related Information for Loans Considered to be Impaired Excluding Purchased Credit Impaired Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureRecordedInvestmentAndRelatedInformationForLoansConsideredToBeImpairedExcludingPurchasedCreditImpairedLoans</Role>
      <ShortName>Recorded Investment and Related Information for Loans Considered to be Impaired Excluding Purchased Credit Impaired Loans (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>154 - Disclosure - Average Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAverageRecordedInvestmentAndInterestIncomeRecognizedOnImpairedLoansExcludingPurchasedCreditImpairedLoans</Role>
      <ShortName>Average Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>155 - Disclosure - Credit Quality - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCreditQualityAdditionalInformation</Role>
      <ShortName>Credit Quality - Additional information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>156 - Disclosure - Balance and Interest Income Related to Impaired Loan Pools (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureBalanceAndInterestIncomeRelatedToImpairedLoanPools</Role>
      <ShortName>Balance and Interest Income Related to Impaired Loan Pools (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>157 - Disclosure - Loans Held for Investment by Internal Credit Risk Grade (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLoansHeldForInvestmentByInternalCreditRiskGrade</Role>
      <ShortName>Loans Held for Investment by Internal Credit Risk Grade (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>158 - Disclosure - Nonaccrual Loans by Loan Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureNonaccrualLoansByLoanClass</Role>
      <ShortName>Nonaccrual Loans by Loan Class (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>159 - Disclosure - Aging of Past Due Loans by Loan Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAgingOfPastDueLoansByLoanClass</Role>
      <ShortName>Aging of Past Due Loans by Loan Class (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>160 - Disclosure - Loans Modified as Troubled Debt Restructurings by Loan Class Segregated by Accrual Status (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLoansModifiedAsTroubledDebtRestructuringsByLoanClassSegregatedByAccrualStatus</Role>
      <ShortName>Loans Modified as Troubled Debt Restructurings by Loan Class Segregated by Accrual Status (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>161 - Disclosure - Loans Modified as Troubled Debt Restructurings by Type of Concession Made and Loan Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLoansModifiedAsTroubledDebtRestructuringsByTypeOfConcessionMadeAndLoanClass</Role>
      <ShortName>Loans Modified as Troubled Debt Restructurings by Type of Concession Made and Loan Class (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>162 - Disclosure - Loans Modified as Troubled Debt Restructurings by Loan Class for which there was Payment Default (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLoansModifiedAsTroubledDebtRestructuringsByLoanClassForWhichThereWasPaymentDefault</Role>
      <ShortName>Loans Modified as Troubled Debt Restructurings by Loan Class for which there was Payment Default (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>163 - Disclosure - Allowance for Loan Losses - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAllowanceForLoanLossesAdditionalInformation</Role>
      <ShortName>Allowance for Loan Losses - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>164 - Disclosure - Aggregate Activity in Allowance For Loan Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAggregateActivityInAllowanceForLoanLosses</Role>
      <ShortName>Aggregate Activity in Allowance For Loan Losses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>165 - Disclosure - Allowance for Loan Losses, Excluding PCI Loans, by Loan Segment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAllowanceForLoanLossesExcludingPCILoansByLoanSegment</Role>
      <ShortName>Allowance for Loan Losses, Excluding PCI Loans, by Loan Segment (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>166 - Disclosure - Allowance For Loan Losses for PCI Loans, by Loan Segment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAllowanceForLoanLossesForPCILoansByLoanSegment</Role>
      <ShortName>Allowance For Loan Losses for PCI Loans, by Loan Segment (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>167 - Disclosure - Allowance for Loan Losses and Recorded Investment in Loans , Excluding PCI Loans, by Loan Class (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAllowanceForLoanLossesAndRecordedInvestmentInLoansExcludingPCILoansByLoanClass</Role>
      <ShortName>Allowance for Loan Losses and Recorded Investment in Loans , Excluding PCI Loans, by Loan Class (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>168 - Disclosure - Allowance for Loan Losses and Recorded Investment in PCI Loans, by Loan Pool (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAllowanceForLoanLossesAndRecordedInvestmentInPCILoansByLoanPool</Role>
      <ShortName>Allowance for Loan Losses and Recorded Investment in PCI Loans, by Loan Pool (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>169 - Disclosure - FDIC Indemnification Asset - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureFDICIndemnificationAssetAdditionalInformation</Role>
      <ShortName>FDIC Indemnification Asset - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>170 - Disclosure - Changes in Receivable from FDIC (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureChangesInReceivableFromFdic</Role>
      <ShortName>Changes in Receivable from FDIC (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>171 - Disclosure - Components of Deposits (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureComponentsOfDeposits</Role>
      <ShortName>Components of Deposits (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>172 - Disclosure - Composition of Borrowings (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCompositionOfBorrowings</Role>
      <ShortName>Composition of Borrowings (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>173 - Disclosure - Borrowings - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureBorrowingsAdditionalInformation</Role>
      <ShortName>Borrowings - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>174 - Disclosure - Contractual Maturities of FHLB Borrowings, by Year (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureContractualMaturitiesOfFHLBBorrowingsByYear</Role>
      <ShortName>Contractual Maturities of FHLB Borrowings, by Year (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>175 - Disclosure - Derivative Instruments and Hedging Activities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureDerivativeInstrumentsAndHedgingActivitiesAdditionalInformation</Role>
      <ShortName>Derivative Instruments and Hedging Activities - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>176 - Disclosure - Aggregate Contractual or Notional Amounts of Derivative Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAggregateContractualOrNotionalAmountsOfDerivativeFinancialInstruments</Role>
      <ShortName>Aggregate Contractual or Notional Amounts of Derivative Financial Instruments (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>177 - Disclosure - Fair Values of Company's Derivatives (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureFairValuesOfCompanysDerivatives</Role>
      <ShortName>Fair Values of Company's Derivatives (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>178 - Disclosure - Effect of Derivative and Hedging Activity, on Statement of Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureEffectOfDerivativeAndHedgingActivityOnStatementOfIncome</Role>
      <ShortName>Effect of Derivative and Hedging Activity, on Statement of Income (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>179 - Disclosure - Net Periodic Benefit Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureNetPeriodicBenefitCost</Role>
      <ShortName>Net Periodic Benefit Cost (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>180 - Disclosure - Components of Accumulated Other Comprehensive Income, Net of Tax (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureComponentsOfAccumulatedOtherComprehensiveIncomeNetOfTax</Role>
      <ShortName>Components of Accumulated Other Comprehensive Income, Net of Tax (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>181 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureReclassificationsOutOfAccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Reclassifications Out of Accumulated Other Comprehensive Income (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>182 - Disclosure - Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureSummaryOfFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasis</Role>
      <ShortName>Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>183 - Disclosure - Assets Measured at Fair Value on Nonrecurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureAssetsMeasuredAtFairValueOnNonrecurringBasis</Role>
      <ShortName>Assets Measured at Fair Value on Nonrecurring Basis (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>184 - Disclosure - Quantitative Information for Assets Measured at Fair Value on Nonrecurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureQuantitativeInformationForAssetsMeasuredAtFairValueOnNonrecurringBasis</Role>
      <ShortName>Quantitative Information for Assets Measured at Fair Value on Nonrecurring Basis (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>185 - Disclosure - Carrying Amount and Fair Value of Company's Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureCarryingAmountAndFairValueOfCompanysFinancialInstruments</Role>
      <ShortName>Carrying Amount and Fair Value of Company's Financial Instruments (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>186 - Disclosure - Off-Balance Sheet Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureOffBalanceSheetFinancialInstruments</Role>
      <ShortName>Off-Balance Sheet Financial Instruments (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>187 - Disclosure - Litigation, Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureLitigationCommitmentsAndContingenciesAdditionalInformation</Role>
      <ShortName>Litigation, Commitments and Contingencies - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>188 - Disclosure - Subsequent Events - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.fcbinc.com/taxonomy/role/DisclosureSubsequentEventsAdditionalInformation</Role>
      <ShortName>Subsequent Events - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Element us-gaap_Deposits had a mix of decimals attribute values: -6 -3.</Log>
    <Log type="Info">Element us-gaap_LoansAndLeasesReceivableNetReportedAmount had a mix of decimals attribute values: -6 -3.</Log>
    <Log type="Info">'Monetary' elements on report '155 - Disclosure - Credit Quality - Additional information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '173 - Disclosure - Borrowings - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '188 - Disclosure - Subsequent Events - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 103 - Statement - Condensed Consolidated Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 104 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 105 - Statement - Condensed Consolidated Statements Of Income</Log>
    <Log type="Info">Process Flow-Through: 106 - Statement - Condensed Consolidated Statements Of Comprehensive Income (Loss)</Log>
    <Log type="Info">Process Flow-Through: 108 - Statement - Condensed Consolidated Statements Of Changes In Stockholders' Equity (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 109 - Statement - Condensed Consolidated Statements Of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>fcbc-20140630.xml</File>
    <File>fcbc-20140630.xsd</File>
    <File>fcbc-20140630_cal.xml</File>
    <File>fcbc-20140630_def.xml</File>
    <File>fcbc-20140630_lab.xml</File>
    <File>fcbc-20140630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
