<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>500</ContextCount>
  <ElementCount>743</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>132</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100030 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100040 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfOperations</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100050 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100060 - Statement - Consolidated Statements of Changes in Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInShareholdersEquity</Role>
      <ShortName>Consolidated Statements of Changes in Shareholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100070 - Statement - Consolidated Statements of Changes in Shareholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfChangesInShareholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Changes in Shareholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100080 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100090 - Statement - Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsParenthetical</Role>
      <ShortName>Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecurities</Role>
      <ShortName>Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Loans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoans</Role>
      <ShortName>Loans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Allowance for Loan Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLosses</Role>
      <ShortName>Allowance for Loan Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Other Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLoss</Role>
      <ShortName>Other Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Premises and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosurePremisesAndEquipment</Role>
      <ShortName>Premises and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Goodwill and Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssets</Role>
      <ShortName>Goodwill and Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Interest-Bearing Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDeposits</Role>
      <ShortName>Interest-Bearing Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Short-Term Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureShortTermBorrowings</Role>
      <ShortName>Short-Term Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Federal Home Loan Bank Advances and Other Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureFederalHomeLoanBankAdvancesAndOtherBorrowings1</Role>
      <ShortName>Federal Home Loan Bank Advances and Other Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Securities Sold Under Agreements to Repurchase</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSoldUnderAgreementsToRepurchase</Role>
      <ShortName>Securities Sold Under Agreements to Repurchase</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Subordinated Debentures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSubordinatedDebentures</Role>
      <ShortName>Subordinated Debentures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlans</Role>
      <ShortName>Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Equity Incentive Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEquityIncentivePlan</Role>
      <ShortName>Equity Incentive Plan</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Fair Value Measurement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurement</Role>
      <ShortName>Fair Value Measurement</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Commitments, Contingencies and Off-Balance-Sheet Risk</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCommitmentsContingenciesAndOffBalanceSheetRisk</Role>
      <ShortName>Commitments, Contingencies and Off-Balance-Sheet Risk</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Capital Requirements and Restriction on Retained Earnings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCapitalRequirementsAndRestrictionOnRetainedEarnings</Role>
      <ShortName>Capital Requirements and Restriction on Retained Earnings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Parent Company Only Condensed Financial Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformation</Role>
      <ShortName>Parent Company Only Condensed Financial Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Earnings per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEarningsPerCommonShare</Role>
      <ShortName>Earnings per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Derivatives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureDerivatives</Role>
      <ShortName>Derivatives</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Qualified Affordable Housing Project Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureQualifiedAffordableHousingProjectInvestments</Role>
      <ShortName>Qualified Affordable Housing Project Investments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Revenue Recognition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRevenueRecognition</Role>
      <ShortName>Revenue Recognition</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitions</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecurities</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Loans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoansTables</Role>
      <ShortName>Loans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoans</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Allowance for Loan Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesTables</Role>
      <ShortName>Allowance for Loan Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLosses</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Other Comprehensive Income (Loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossTables</Role>
      <ShortName>Other Comprehensive Income (Loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLoss</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Premises and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosurePremisesAndEquipmentTables</Role>
      <ShortName>Premises and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosurePremisesAndEquipment</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Goodwill and Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsTables</Role>
      <ShortName>Goodwill and Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssets</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Interest-Bearing Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDepositsTables</Role>
      <ShortName>Interest-Bearing Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDeposits</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Short-Term Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureShortTermBorrowingsTables</Role>
      <ShortName>Short-Term Borrowings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureShortTermBorrowings</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Federal Home Loan Bank Advances and Other Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureFederalHomeLoanBankAdvancesAndOtherBorrowingsTables</Role>
      <ShortName>Federal Home Loan Bank Advances and Other Borrowings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/DisclosureFederalHomeLoanBankAdvancesAndOtherBorrowings1</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Securities Sold Under Agreements to Repurchase (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSoldUnderAgreementsToRepurchaseTables</Role>
      <ShortName>Securities Sold Under Agreements to Repurchase (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSoldUnderAgreementsToRepurchase</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Subordinated Debentures (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureSubordinatedDebenturesTables</Role>
      <ShortName>Subordinated Debentures (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSubordinatedDebentures</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxes</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Retirement Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansTables</Role>
      <ShortName>Retirement Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlans</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Equity Incentive Plan (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEquityIncentivePlanTables</Role>
      <ShortName>Equity Incentive Plan (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEquityIncentivePlan</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100530 - Disclosure - Fair Value Measurement (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementTables</Role>
      <ShortName>Fair Value Measurement (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurement</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100540 - Disclosure - Commitments, Contingencies and Off-Balance-Sheet Risk (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCommitmentsContingenciesAndOffBalanceSheetRiskTables</Role>
      <ShortName>Commitments, Contingencies and Off-Balance-Sheet Risk (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCommitmentsContingenciesAndOffBalanceSheetRisk</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Capital Requirements and Restriction on Retained Earnings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCapitalRequirementsAndRestrictionOnRetainedEarningsTables</Role>
      <ShortName>Capital Requirements and Restriction on Retained Earnings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCapitalRequirementsAndRestrictionOnRetainedEarnings</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Parent Company Only Condensed Financial Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformationTables</Role>
      <ShortName>Parent Company Only Condensed Financial Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformation</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100570 - Disclosure - Earnings per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEarningsPerCommonShareTables</Role>
      <ShortName>Earnings per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEarningsPerCommonShare</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Derivatives (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureDerivativesTables</Role>
      <ShortName>Derivatives (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureDerivatives</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Revenue Recognition (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRevenueRecognitionTables</Role>
      <ShortName>Revenue Recognition (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRevenueRecognition</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeases</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Acquisitions - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsAdditionalInformationDetails</Role>
      <ShortName>Acquisitions - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Acquisitions - Schedule of Estimated Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsScheduleOfEstimatedAmortizationExpenseDetails</Role>
      <ShortName>Acquisitions - Schedule of Estimated Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100640 - Disclosure - Acquisitions - Summary of Financial Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsSummaryOfFinancialInformationDetails</Role>
      <ShortName>Acquisitions - Summary of Financial Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>100650 - Disclosure - Acquisitions - Summary of Pro Forma Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsSummaryOfProFormaInformationDetails</Role>
      <ShortName>Acquisitions - Summary of Pro Forma Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>100660 - Disclosure - Acquisitions - Summary of Estimated Fair Values of the Assets Acquired and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsSummaryOfEstimatedFairValuesOfTheAssetsAcquiredAndLiabilitiesDetails</Role>
      <ShortName>Acquisitions - Summary of Estimated Fair Values of the Assets Acquired and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>100670 - Disclosure - Acquisitions - Summary of Estimated Fair Values of the Assets Acquired and Liabilities (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsSummaryOfEstimatedFairValuesOfTheAssetsAcquiredAndLiabilitiesParentheticalDetails</Role>
      <ShortName>Acquisitions - Summary of Estimated Fair Values of the Assets Acquired and Liabilities (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>100680 - Disclosure - Acquisitions - Summary of Acquired and Accounted for in Accordance With ASC 310-30 (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureAcquisitionsSummaryOfAcquiredAndAccountedForInAccordanceWithAsc31030Details</Role>
      <ShortName>Acquisitions - Summary of Acquired and Accounted for in Accordance With ASC 310-30 (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>100690 - Disclosure - Securities - Available for Sale Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesAvailableForSaleSecuritiesDetail</Role>
      <ShortName>Securities - Available for Sale Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>100700 - Disclosure - Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesAmortizedCostAndFairValueOfSecuritiesByContractualMaturityDetail</Role>
      <ShortName>Securities - Amortized Cost and Fair Value of Securities by Contractual Maturity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>100710 - Disclosure - Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesAdditionalInformationDetail</Role>
      <ShortName>Securities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>100720 - Disclosure - Securities - Proceeds from Sales of Securities, Gross Realized Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesProceedsFromSalesOfSecuritiesGrossRealizedGainsAndLossesDetail</Role>
      <ShortName>Securities - Proceeds from Sales of Securities, Gross Realized Gains and Losses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>100730 - Disclosure - Securities - Securities with Unrealized Losses Not Recognized in Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSecuritiesWithUnrealizedLossesNotRecognizedInIncomeDetail</Role>
      <ShortName>Securities - Securities with Unrealized Losses Not Recognized in Income (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>100740 - Disclosure - Securities - Schedule of Net Gains and Losses on Equity Investments Recognized in Earnings and Portion of Unrealized Gains and Losses for Period that Relates to Equity Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesScheduleOfNetGainsAndLossesOnEquityInvestmentsRecognizedInEarningsAndPortionOfUnrealizedGainsAndLossesForPeriodThatRelatesToEquityInvestmentsDetails</Role>
      <ShortName>Securities - Schedule of Net Gains and Losses on Equity Investments Recognized in Earnings and Portion of Unrealized Gains and Losses for Period that Relates to Equity Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>100750 - Disclosure - Loans - Loan Balances (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoansLoanBalancesDetail</Role>
      <ShortName>Loans - Loan Balances (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>100760 - Disclosure - Loans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoansAdditionalInformationDetail</Role>
      <ShortName>Loans - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>100770 - Disclosure - Loans - Scheduled Maturities of Lease Financing Receivables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureLoansScheduledMaturitiesOfLeaseFinancingReceivablesDetails</Role>
      <ShortName>Loans - Scheduled Maturities of Lease Financing Receivables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>100780 - Disclosure - Loans - Loans to Directors and Executive Officers Including Immediate Families (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLoansLoansToDirectorsAndExecutiveOfficersIncludingImmediateFamiliesDetail</Role>
      <ShortName>Loans - Loans to Directors and Executive Officers Including Immediate Families (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>100790 - Disclosure - Allowance for Loan Losses - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesAdditionalInformationDetail</Role>
      <ShortName>Allowance for Loan Losses - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>100800 - Disclosure - Allowance for Loan Losses - Changes in the Allowance for Loan Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesChangesInAllowanceForLoanLossesDetail</Role>
      <ShortName>Allowance for Loan Losses - Changes in the Allowance for Loan Losses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>100810 - Disclosure - Allowance for Loan Losses - Ending Allocation of Allowance for Loan Losses and Loan Balances Outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesEndingAllocationOfAllowanceForLoanLossesAndLoanBalancesOutstandingDetail</Role>
      <ShortName>Allowance for Loan Losses - Ending Allocation of Allowance for Loan Losses and Loan Balances Outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>100820 - Disclosure - Allowance for Loan Losses - Credit Exposures by Internally Assigned Grades (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesCreditExposuresByInternallyAssignedGradesDetail</Role>
      <ShortName>Allowance for Loan Losses - Credit Exposures by Internally Assigned Grades (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>100830 - Disclosure - Allowance for Loan Losses - Performing and Nonperforming Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesPerformingAndNonperformingLoansDetail</Role>
      <ShortName>Allowance for Loan Losses - Performing and Nonperforming Loans (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>100840 - Disclosure - Allowance for Loan Losses - Aging Analysis of Past Due Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesAgingAnalysisOfPastDueLoansDetail</Role>
      <ShortName>Allowance for Loan Losses - Aging Analysis of Past Due Loans (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>100850 - Disclosure - Allowance for Loan Losses - Summary of Nonaccrual Loans Excluding Purchased Credit-Impaired (PCI) Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesSummaryOfNonaccrualLoansExcludingPurchasedCreditImpairedPCILoansDetail</Role>
      <ShortName>Allowance for Loan Losses - Summary of Nonaccrual Loans Excluding Purchased Credit-Impaired (PCI) Loans (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>100880 - Disclosure - Allowance for Loan Losses - Impaired Financing Receivables Excluding PCI Loans - Recorded Investment and Unpaid Principal Balances (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesImpairedFinancingReceivablesExcludingPCILoansRecordedInvestmentAndUnpaidPrincipalBalancesDetail</Role>
      <ShortName>Allowance for Loan Losses - Impaired Financing Receivables Excluding PCI Loans - Recorded Investment and Unpaid Principal Balances (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>100890 - Disclosure - Allowance for Loan Losses - Impaired Loans - Average Recorded Investment and Interest Income Recognized (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesImpairedLoansAverageRecordedInvestmentAndInterestIncomeRecognizedDetail</Role>
      <ShortName>Allowance for Loan Losses - Impaired Loans - Average Recorded Investment and Interest Income Recognized (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>100900 - Disclosure - Allowance for Loan Losses - Schedule of Changes in Amortized Yield for PCI Loans (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesScheduleOfChangesInAmortizedYieldForPCILoansDetail</Role>
      <ShortName>Allowance for Loan Losses - Schedule of Changes in Amortized Yield for PCI Loans (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>100910 - Disclosure - Allowance for Loan Losses - Schedule of Loans Acquired and Accounted (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureAllowanceForLoanLossesScheduleOfLoansAcquiredAndAccountedDetail</Role>
      <ShortName>Allowance for Loan Losses - Schedule of Loans Acquired and Accounted (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>100920 - Disclosure - Other Comprehensive Income (Loss) - Components of Other Comprehensive Income Loss (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossComponentsOfOtherComprehensiveIncomeLossDetail</Role>
      <ShortName>Other Comprehensive Income (Loss) - Components of Other Comprehensive Income Loss (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>100930 - Disclosure - Other Comprehensive Income (Loss) - Changes in Each Component of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossChangesInEachComponentOfAccumulatedOtherComprehensiveIncomeLossNetOfTaxDetail</Role>
      <ShortName>Other Comprehensive Income (Loss) - Changes in Each Component of Accumulated Other Comprehensive Income (Loss), Net of Tax (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>100940 - Disclosure - Other Comprehensive Income (Loss) - Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Loss (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossAmountsReclassifiedOutOfEachComponentOfAccumulatedOtherComprehensiveLossDetail</Role>
      <ShortName>Other Comprehensive Income (Loss) - Amounts Reclassified Out of Each Component of Accumulated Other Comprehensive Loss (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>100950 - Disclosure - Premises and Equipment - Year-End Premises and Equipment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosurePremisesAndEquipmentYearEndPremisesAndEquipmentDetail</Role>
      <ShortName>Premises and Equipment - Year-End Premises and Equipment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>100960 - Disclosure - Premises and Equipment - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosurePremisesAndEquipmentAdditionalInformationDetail</Role>
      <ShortName>Premises and Equipment - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>100970 - Disclosure - Goodwill and Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>100980 - Disclosure - Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfAcquiredIntangibleAssetsDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>100990 - Disclosure - Goodwill and Intangible Assets - Schedule of Mortgage Servicing Rights (MSRs) and Related Valuation Allowance (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfMortgageServicingRightsMsrsAndRelatedValuationAllowanceDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Schedule of Mortgage Servicing Rights (MSRs) and Related Valuation Allowance (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>101000 - Disclosure - Goodwill and Intangible Assets - Schedule of Estimated Amortization Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureGoodwillAndIntangibleAssetsScheduleOfEstimatedAmortizationExpenseDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Schedule of Estimated Amortization Expense (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>101010 - Disclosure - Interest-Bearing Deposits - Summary of Interest-Bearing Deposits (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDepositsSummaryOfInterestBearingDepositsDetail</Role>
      <ShortName>Interest-Bearing Deposits - Summary of Interest-Bearing Deposits (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>101020 - Disclosure - Interest-Bearing Deposits - Scheduled Maturities of Certificates of Deposit (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDepositsScheduledMaturitiesOfCertificatesOfDepositDetail</Role>
      <ShortName>Interest-Bearing Deposits - Scheduled Maturities of Certificates of Deposit (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>101030 - Disclosure - Interest-Bearing Deposits - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureInterestBearingDepositsAdditionalInformationDetail</Role>
      <ShortName>Interest-Bearing Deposits - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>101040 - Disclosure - Short-Term Borrowings - Summary of Federal Funds Purchased and Other Short-term Borrowings (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureShortTermBorrowingsSummaryOfFederalFundsPurchasedAndOtherShortTermBorrowingsDetail</Role>
      <ShortName>Short-Term Borrowings - Summary of Federal Funds Purchased and Other Short-term Borrowings (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>101050 - Disclosure - Short-Term Borrowings - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureShorttermBorrowingsAdditionalInformationDetail</Role>
      <ShortName>Short-Term Borrowings - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>101060 - Disclosure - Federal Home Loan Bank Advances and Other Borrowings - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureFederalHomeLoanBankAdvancesAndOtherBorrowingsAdditionalInformationDetail</Role>
      <ShortName>Federal Home Loan Bank Advances and Other Borrowings - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>101070 - Disclosure - Federal Home Loan Bank Advances and Other Borrowings - Scheduled Principal Reductions of Federal Home Loan Bank Advances Outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureFederalHomeLoanBankAdvancesAndOtherBorrowingsScheduledPrincipalReductionsOfFederalHomeLoanBankAdvancesOutstandingDetail</Role>
      <ShortName>Federal Home Loan Bank Advances and Other Borrowings - Scheduled Principal Reductions of Federal Home Loan Bank Advances Outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>101080 - Disclosure - Securities Sold Under Agreements To Repurchase - Summary of Securities Pledged as Collateral Under Repurchase Agreements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSoldUnderAgreementsToRepurchaseSummaryOfSecuritiesPledgedAsCollateralUnderRepurchaseAgreementsDetail</Role>
      <ShortName>Securities Sold Under Agreements To Repurchase - Summary of Securities Pledged as Collateral Under Repurchase Agreements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>101090 - Disclosure - Securities Sold Under Agreements to Repurchase - Schedule of Securities Sold Under Agreements to Repurchase (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSecuritiesSoldUnderAgreementsToRepurchaseScheduleOfSecuritiesSoldUnderAgreementsToRepurchaseDetail</Role>
      <ShortName>Securities Sold Under Agreements to Repurchase - Schedule of Securities Sold Under Agreements to Repurchase (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>101100 - Disclosure - Subordinated Debentures - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSubordinatedDebenturesAdditionalInformationDetail</Role>
      <ShortName>Subordinated Debentures - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>101110 - Disclosure - Subordinated Debentures - Schedule of Subordinated Debentures (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureSubordinatedDebenturesScheduleOfSubordinatedDebenturesDetails</Role>
      <ShortName>Subordinated Debentures - Schedule of Subordinated Debentures (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>101120 - Disclosure - Subordinated Debentures - Schedule of Subordinated Debentures (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureSubordinatedDebenturesScheduleOfSubordinatedDebenturesParentheticalDetails</Role>
      <ShortName>Subordinated Debentures - Schedule of Subordinated Debentures (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>101130 - Disclosure - Income Taxes - Schedule of Income Tax (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesScheduleOfIncomeTaxDetail</Role>
      <ShortName>Income Taxes - Schedule of Income Tax (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>101140 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>101150 - Disclosure - Income Taxes - Effective Tax Rates Differed from Statutory Federal Income Tax Rate (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesEffectiveTaxRatesDifferedFromStatutoryFederalIncomeTaxRateDetail</Role>
      <ShortName>Income Taxes - Effective Tax Rates Differed from Statutory Federal Income Tax Rate (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>101160 - Disclosure - Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureIncomeTaxesSummaryOfDeferredTaxAssetsAndLiabilitiesDetail</Role>
      <ShortName>Income Taxes - Summary of Deferred Tax Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>101170 - Disclosure - Retirement Plans - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansAdditionalInformationDetail</Role>
      <ShortName>Retirement Plans - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>101180 - Disclosure - Retirement Plans - Information about Pension Plan (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansInformationAboutPensionPlanDetail</Role>
      <ShortName>Retirement Plans - Information about Pension Plan (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>101190 - Disclosure - Retirement Plans - Components of Net Periodic Pension Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansComponentsOfNetPeriodicPensionExpenseDetail</Role>
      <ShortName>Retirement Plans - Components of Net Periodic Pension Expense (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>101200 - Disclosure - Retirement Plans - Weighted Average Assumptions Used to Determine Benefit Obligations and Net Periodic Pension Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansWeightedAverageAssumptionsUsedToDetermineBenefitObligationsAndNetPeriodicPensionCostDetail</Role>
      <ShortName>Retirement Plans - Weighted Average Assumptions Used to Determine Benefit Obligations and Net Periodic Pension Cost (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>101210 - Disclosure - Retirement Plans - Schedule of Pension Plan Asset Allocation and Target Allocation by Asset Category (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansScheduleOfPensionPlanAssetAllocationAndTargetAllocationByAssetCategoryDetail</Role>
      <ShortName>Retirement Plans - Schedule of Pension Plan Asset Allocation and Target Allocation by Asset Category (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>101220 - Disclosure - Retirement Plans - Summary of Investments Measured at Fair Value Based on NAV Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansSummaryOfInvestmentsMeasuredAtFairValueBasedOnNAVPerShareDetail</Role>
      <ShortName>Retirement Plans - Summary of Investments Measured at Fair Value Based on NAV Per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>101230 - Disclosure - Retirement Plans - Summary of Expected Benefit Payments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRetirementPlansSummaryOfExpectedBenefitPaymentsDetail</Role>
      <ShortName>Retirement Plans - Summary of Expected Benefit Payments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>101240 - Disclosure - Equity Incentive Plan - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEquityIncentivePlanAdditionalInformationDetail</Role>
      <ShortName>Equity Incentive Plan - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>101250 - Disclosure - Equity Incentive Plan - Summary of Company's Restricted Stock (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEquityIncentivePlanSummaryOfCompanySRestrictedStockDetail</Role>
      <ShortName>Equity Incentive Plan - Summary of Company's Restricted Stock (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>101260 - Disclosure - Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementAssetsAndLiabilitiesMeasuredAtFairValueDetail</Role>
      <ShortName>Fair Value Measurement - Assets and Liabilities Measured at Fair Value (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>101270 - Disclosure - Fair Value Measurement - Quantitative Information about Level 3 Fair Value Measurements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementQuantitativeInformationAboutLevel3FairValueMeasurementsDetail</Role>
      <ShortName>Fair Value Measurement - Quantitative Information about Level 3 Fair Value Measurements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>101280 - Disclosure - Fair Value Measurement - Carrying Amount and Fair Value of Financial Instruments Carried at Amortized Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureFairValueMeasurementCarryingAmountAndFairValueOfFinancialInstrumentsCarriedAtAmortizedCostDetail</Role>
      <ShortName>Fair Value Measurement - Carrying Amount and Fair Value of Financial Instruments Carried at Amortized Cost (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>101290 - Disclosure - Commitments, Contingencies and Off-Balance-Sheet Risk - Contractual Amounts of Financial Instruments with Off-Balance-Sheet Risk (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCommitmentsContingenciesAndOffBalanceSheetRiskContractualAmountsOfFinancialInstrumentsWithOffBalanceSheetRiskDetail</Role>
      <ShortName>Commitments, Contingencies and Off-Balance-Sheet Risk - Contractual Amounts of Financial Instruments with Off-Balance-Sheet Risk (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>125</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>101300 - Disclosure - Commitments, Contingencies and Off-Balance-Sheet Risk - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCommitmentsContingenciesAndOffBalanceSheetRiskAdditionalInformationDetail</Role>
      <ShortName>Commitments, Contingencies and Off-Balance-Sheet Risk - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>126</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>101320 - Disclosure - Capital Requirements and Restriction on Retained Earnings - Actual Capital Levels and Minimum Required Capital Levels (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCapitalRequirementsAndRestrictionOnRetainedEarningsActualCapitalLevelsAndMinimumRequiredCapitalLevelsDetail</Role>
      <ShortName>Capital Requirements and Restriction on Retained Earnings - Actual Capital Levels and Minimum Required Capital Levels (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>127</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>101330 - Disclosure - Capital Requirements and Restriction on Retained Earnings - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureCapitalRequirementsAndRestrictionOnRetainedEarningsAdditionalInformationDetail</Role>
      <ShortName>Capital Requirements and Restriction on Retained Earnings - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>101340 - Disclosure - Parent Company Only Condensed Financial Information - Schedule of Condensed Balance Sheets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformationScheduleOfCondensedBalanceSheetsDetail</Role>
      <ShortName>Parent Company Only Condensed Financial Information - Schedule of Condensed Balance Sheets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>101350 - Disclosure - Parent Company Only Condensed Financial Information - Schedule of Condensed Statements of Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformationScheduleOfCondensedStatementsOfOperationsDetail</Role>
      <ShortName>Parent Company Only Condensed Financial Information - Schedule of Condensed Statements of Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>101360 - Disclosure - Parent Company Only Condensed Financial Information - Schedule of Condensed Statements of Cash Flows (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureParentCompanyOnlyCondensedFinancialInformationScheduleOfCondensedStatementsOfCashFlowsDetail</Role>
      <ShortName>Parent Company Only Condensed Financial Information - Schedule of Condensed Statements of Cash Flows (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>101380 - Disclosure - Earnings per Common Share - Computation of Basic and Diluted Earnings per Common Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureEarningsPerCommonShareComputationOfBasicAndDilutedEarningsPerCommonShareDetail</Role>
      <ShortName>Earnings per Common Share - Computation of Basic and Diluted Earnings per Common Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>101390 - Disclosure - Derivatives - Summary of Interest Rate Swap Transactions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureDerivativesSummaryOfInterestRateSwapTransactionsDetail</Role>
      <ShortName>Derivatives - Summary of Interest Rate Swap Transactions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>101400 - Disclosure - Derivatives - Summary Of Gross Notional Amount Derivatives (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureDerivativesSummaryOfGrossNotionalAmountDerivativesDetail</Role>
      <ShortName>Derivatives - Summary Of Gross Notional Amount Derivatives (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>134</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>101410 - Disclosure - Derivatives - Summary of Gain or loss On Derivatives (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureDerivativesSummaryOfGainOrLossOnDerivativesDetail</Role>
      <ShortName>Derivatives - Summary of Gain or loss On Derivatives (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>135</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R136.htm</HtmlFileName>
      <LongName>101420 - Disclosure - Derivatives - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureDerivativesAdditionalInformationDetail</Role>
      <ShortName>Derivatives - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>136</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>101430 - Disclosure - Qualified Affordable Housing Project Investments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureQualifiedAffordableHousingProjectInvestmentsAdditionalInformationDetail</Role>
      <ShortName>Qualified Affordable Housing Project Investments - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>137</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>101440 - Disclosure - Revenue Recognition - Summary of Noninterest Income Segregated By Revenue Streams In-scope and Out-of-scope of Topic 606 (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureRevenueRecognitionSummaryOfNoninterestIncomeSegregatedByRevenueStreamsInScopeAndOutOfScopeOfTopic606Detail</Role>
      <ShortName>Revenue Recognition - Summary of Noninterest Income Segregated By Revenue Streams In-scope and Out-of-scope of Topic 606 (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>138</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R139.htm</HtmlFileName>
      <LongName>101450 - Disclosure - Leases - Summary of Balance Sheet Information Related to Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeasesSummaryOfBalanceSheetInformationRelatedToOperatingLeasesDetail</Role>
      <ShortName>Leases - Summary of Balance Sheet Information Related to Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>139</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R140.htm</HtmlFileName>
      <LongName>101460 - Disclosure - Leases - Summary of Cost Components of Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeasesSummaryOfCostComponentsOfOperatingLeasesDetail</Role>
      <ShortName>Leases - Summary of Cost Components of Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>140</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>101470 - Disclosure - Leases - Summary of Maturities of Operating and Finance Lease Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeasesSummaryOfMaturitiesOfOperatingAndFinanceLeaseLiabilitiesDetail</Role>
      <ShortName>Leases - Summary of Maturities of Operating and Finance Lease Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>141</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>101480 - Disclosure - Leases - Summary of Weighted Average Remaining Lease Terms And Discount Rates For Operating Leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureLeasesSummaryOfWeightedAverageRemainingLeaseTermsAndDiscountRatesForOperatingLeasesDetail</Role>
      <ShortName>Leases - Summary of Weighted Average Remaining Lease Terms And Discount Rates For Operating Leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>142</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R143.htm</HtmlFileName>
      <LongName>101490 - Disclosure - Leases - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/DisclosureLeasesAdditionalInformationDetail</Role>
      <ShortName>Leases - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>143</Position>
    </Report>
    <Report instance="civb-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R144.htm</HtmlFileName>
      <LongName>101500 - Disclosure - Subsequent Events - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.civb.com/20221231/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetail</Role>
      <ShortName>Subsequent Events - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>144</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Warning">[ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 9 fact(s) appearing in ix:hidden were eligible for transformation: civb:EmployeeStockOwnershipPlansMinimumWorkingPeriodForParticipationInEsop, civb:MinimumEligibleAgeToParticipateInPlans, us-gaap:FairValueInvestmentsEntitiesThatCalculateNetAssetValuePerShareInvestmentRedemptionNoticePeriod1, us-gaap:FiniteLivedIntangibleAssetUsefulLife, us-gaap:LessorDirectFinancingLeaseTermOfContract1, us-gaap:PropertyPlantAndEquipmentUsefulLife -  civb-20221231.htm 8</Log>
  </Logs>
  <InputFiles>
    <File doctype="10-K" original="civb-20221231.htm">civb-20221231.htm</File>
    <File>civb-20221231.xsd</File>
    <File>civb-20221231_cal.xml</File>
    <File>civb-20221231_def.xml</File>
    <File>civb-20221231_lab.xml</File>
    <File>civb-20221231_pre.xml</File>
    <File>civb-ex21_1.htm</File>
    <File>civb-ex23_1.htm</File>
    <File>civb-ex23_2.htm</File>
    <File>civb-ex31_1.htm</File>
    <File>civb-ex31_2.htm</File>
    <File>civb-ex32_1.htm</File>
    <File>civb-ex32_2.htm</File>
    <File>civb-ex4_3.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>img124214296_0.jpg</File>
    <File>img124214296_1.jpg</File>
    <File>img124214296_2.jpg</File>
    <File>img124214296_3.jpg</File>
    <File>img124214296_4.jpg</File>
    <File>img124214296_5.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="3">http://fasb.org/srt/2022</BaseTaxonomy>
    <BaseTaxonomy items="2097">http://fasb.org/us-gaap/2022</BaseTaxonomy>
    <BaseTaxonomy items="38">http://xbrl.sec.gov/dei/2022</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
