<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.22.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>391</ContextCount>
  <ElementCount>622</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>98</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover Page</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CoverPage</Role>
      <ShortName>Cover Page</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Document - Audit Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/AuditInformation</Role>
      <ShortName>Audit Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - Statement - Consolidated Statements of Financial Condition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofFinancialCondition</Role>
      <ShortName>Consolidated Statements of Financial Condition</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - Consolidated Statements of Financial Condition (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofFinancialConditionParentheticals</Role>
      <ShortName>Consolidated Statements of Financial Condition (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - Statement - Consolidated Statement of Comprehensive (Loss) Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementofComprehensiveLossIncome</Role>
      <ShortName>Consolidated Statement of Comprehensive (Loss) Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - Statement - Consolidated Statements of Changes in Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofChangesinStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Changes in Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Statement - Consolidated Statements of Changes in Stockholders' Equity (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofChangesinStockholdersEquityParentheticals</Role>
      <ShortName>Consolidated Statements of Changes in Stockholders' Equity (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - Statement - Consolidated Statements of Cash Flows (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ConsolidatedStatementsofCashFlowsParentheticals</Role>
      <ShortName>Consolidated Statements of Cash Flows (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/Securities</Role>
      <ShortName>Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Loans and Related Allowance for Loan Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLosses</Role>
      <ShortName>Loans and Related Allowance for Loan Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Premises and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/PremisesandEquipment</Role>
      <ShortName>Premises and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - Disclosure - Goodwill and Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/GoodwillandIntangibleAssets</Role>
      <ShortName>Goodwill and Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/Deposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Short-term Borrowings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ShorttermBorrowings</Role>
      <ShortName>Short-term Borrowings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - Disclosure - Other Borrowed Funds</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherBorrowedFunds</Role>
      <ShortName>Other Borrowed Funds</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>0000020 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>0000021 - Disclosure - Employee Benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefits</Role>
      <ShortName>Employee Benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>0000022 - Disclosure - Commitments and Contingent Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CommitmentsandContingentLiabilities</Role>
      <ShortName>Commitments and Contingent Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>0000023 - Disclosure - Stockholders' Equity and Regulatory Capital</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/StockholdersEquityandRegulatoryCapital</Role>
      <ShortName>Stockholders' Equity and Regulatory Capital</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>0000024 - Disclosure - Operating Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OperatingLeases</Role>
      <ShortName>Operating Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>0000025 - Disclosure - Mortgage Servicing Rights</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/MortgageServicingRights</Role>
      <ShortName>Mortgage Servicing Rights</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>0000026 - Disclosure - Fair Value Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosure</Role>
      <ShortName>Fair Value Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>0000027 - Disclosure - Other Noninterest Expense</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherNoninterestExpense</Role>
      <ShortName>Other Noninterest Expense</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>0000028 - Disclosure - Condensed Financial Statements of Parent Company</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompany</Role>
      <ShortName>Condensed Financial Statements of Parent Company</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>0000029 - Disclosure - Segment Reporting and Related Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SegmentReportingandRelatedInformation</Role>
      <ShortName>Segment Reporting and Related Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>0000030 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>0000031 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/EarningsPerShare</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>0000032 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/Securities</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>0000033 - Disclosure - Loans and Related Allowance for Loan Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesTables</Role>
      <ShortName>Loans and Related Allowance for Loan Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLosses</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>0000034 - Disclosure - Premises and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/PremisesandEquipmentTables</Role>
      <ShortName>Premises and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/PremisesandEquipment</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>0000035 - Disclosure - Goodwill and Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/GoodwillandIntangibleAssetsTables</Role>
      <ShortName>Goodwill and Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/GoodwillandIntangibleAssets</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>0000036 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/DepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/Deposits</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>0000037 - Disclosure - Short-term Borrowings (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ShorttermBorrowingsTables</Role>
      <ShortName>Short-term Borrowings (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/ShorttermBorrowings</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>0000038 - Disclosure - Other Borrowed Funds (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherBorrowedFundsTables</Role>
      <ShortName>Other Borrowed Funds (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/OtherBorrowedFunds</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>0000039 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/IncomeTaxes</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>0000040 - Disclosure - Employee Benefits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefitsTables</Role>
      <ShortName>Employee Benefits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/EmployeeBenefits</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>0000041 - Disclosure - Commitments and Contingent Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CommitmentsandContingentLiabilitiesTables</Role>
      <ShortName>Commitments and Contingent Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/CommitmentsandContingentLiabilities</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>0000042 - Disclosure - Stockholders' Equity and Regulatory Capital (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/StockholdersEquityandRegulatoryCapitalTables</Role>
      <ShortName>Stockholders' Equity and Regulatory Capital (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/StockholdersEquityandRegulatoryCapital</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>0000043 - Disclosure - Operating Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OperatingLeasesTables</Role>
      <ShortName>Operating Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/OperatingLeases</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>0000044 - Disclosure - Mortgage Servicing Rights (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/MortgageServicingRightsTables</Role>
      <ShortName>Mortgage Servicing Rights (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/MortgageServicingRights</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>0000045 - Disclosure - Fair Value Disclosure (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosureTables</Role>
      <ShortName>Fair Value Disclosure (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/FairValueDisclosure</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>0000046 - Disclosure - Other Noninterest Expense (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherNoninterestExpenseTables</Role>
      <ShortName>Other Noninterest Expense (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/OtherNoninterestExpense</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>0000047 - Disclosure - Condensed Financial Statements of Parent Company (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompanyTables</Role>
      <ShortName>Condensed Financial Statements of Parent Company (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompany</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>0000048 - Disclosure - Segment Reporting and Related Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SegmentReportingandRelatedInformationTables</Role>
      <ShortName>Segment Reporting and Related Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/SegmentReportingandRelatedInformation</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>0000049 - Disclosure - Summary of Significant Accounting Policies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SummaryofSignificantAccountingPoliciesDetails</Role>
      <ShortName>Summary of Significant Accounting Policies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/SummaryofSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>0000050 - Disclosure - Earnings Per Share - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EarningsPerShareNarrativeDetails</Role>
      <ShortName>Earnings Per Share - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>0000051 - Disclosure - Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EarningsPerShareBasicandDilutedEarningsPerCommonShareDetails</Role>
      <ShortName>Earnings Per Share - Basic and Diluted Earnings Per Common Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>0000052 - Disclosure - Earnings Per Share - Schedule of Computation of Diluted Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EarningsPerShareScheduleofComputationofDilutedEarningsPerShareDetails</Role>
      <ShortName>Earnings Per Share - Schedule of Computation of Diluted Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>0000053 - Disclosure - Securities - Amortized Cost and Fair Value of Investment Securities Available-for-sale (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesAmortizedCostandFairValueofInvestmentSecuritiesAvailableforsaleDetails</Role>
      <ShortName>Securities - Amortized Cost and Fair Value of Investment Securities Available-for-sale (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>0000054 - Disclosure - Securities - Gross Unrealized Losses and Fair Value by Investment Category and Continuous Unrealized Loss Position (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesGrossUnrealizedLossesandFairValuebyInvestmentCategoryandContinuousUnrealizedLossPositionDetails</Role>
      <ShortName>Securities - Gross Unrealized Losses and Fair Value by Investment Category and Continuous Unrealized Loss Position (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>0000055 - Disclosure - Securities - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesNarrativeDetails</Role>
      <ShortName>Securities - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>0000056 - Disclosure - Securities - Maturities of Investment Securities Available-for-sale and Held-to-maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesMaturitiesofInvestmentSecuritiesAvailableforsaleandHeldtomaturityDetails</Role>
      <ShortName>Securities - Maturities of Investment Securities Available-for-sale and Held-to-maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>0000057 - Disclosure - Securities - Gains (Losses) of Sales of Available-for-sale Investment Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SecuritiesGainsLossesofSalesofAvailableforsaleInvestmentSecuritiesDetails</Role>
      <ShortName>Securities - Gains (Losses) of Sales of Available-for-sale Investment Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>0000058 - Disclosure - Loans and Related Allowance for Loan Losses - Composition of Loan Portfolio (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesCompositionofLoanPortfolioDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Composition of Loan Portfolio (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>0000059 - Disclosure - Loans and Related Allowance for Loan Losses - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesNarrativeDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>0000060 - Disclosure - Loans and Related Allowance for Loan Losses - Summary of PPP Loan Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesSummaryofPPPLoanActivityDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Summary of PPP Loan Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>0000061 - Disclosure - Loans and Related Allowance for Loan Losses - Credit Quality Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesCreditQualityInformationDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Credit Quality Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>0000062 - Disclosure - Loans and Related Allowance for Loan Losses - Loans by Aging Categories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesLoansbyAgingCategoriesDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Loans by Aging Categories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>0000063 - Disclosure - Loans and Related Allowance for Loan Losses - Impaired Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesImpairedLoansDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Impaired Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>0000064 - Disclosure - Loans and Related Allowance for Loan Losses - Loans Classified as TDRs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesLoansClassifiedasTDRsDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Loans Classified as TDRs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>0000065 - Disclosure - Loans and Related Allowance for Loan Losses - Activity in the Allowance for Loan Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesActivityintheAllowanceforLoanLossesDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Activity in the Allowance for Loan Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>0000066 - Disclosure - Loans and Related Allowance for Loan Losses - Loans Summarized by Individually Evaluated for Impairment and Collectively Evaluated for Potential Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesLoansSummarizedbyIndividuallyEvaluatedforImpairmentandCollectivelyEvaluatedforPotentialLossesDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Loans Summarized by Individually Evaluated for Impairment and Collectively Evaluated for Potential Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>0000067 - Disclosure - Loans and Related Allowance for Loan Losses - Accretable Discount on Loans Acquired at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesAccretableDiscountonLoansAcquiredatFairValueDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Accretable Discount on Loans Acquired at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>0000068 - Disclosure - Loans and Related Allowance for Loan Losses - Related Party Loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/LoansandRelatedAllowanceforLoanLossesRelatedPartyLoansDetails</Role>
      <ShortName>Loans and Related Allowance for Loan Losses - Related Party Loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>0000069 - Disclosure - Premises and Equipment - Classifications of Premises and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/PremisesandEquipmentClassificationsofPremisesandEquipmentDetails</Role>
      <ShortName>Premises and Equipment - Classifications of Premises and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>0000070 - Disclosure - Premises and Equipment - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/PremisesandEquipmentNarrativeDetails</Role>
      <ShortName>Premises and Equipment - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>0000071 - Disclosure - Goodwill and Intangible Assets - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/GoodwillandIntangibleAssetsAdditionalInformationDetails</Role>
      <ShortName>Goodwill and Intangible Assets - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>0000072 - Disclosure - Goodwill and Intangible Assets - Summary of Intangible Assets Subject to Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/GoodwillandIntangibleAssetsSummaryofIntangibleAssetsSubjecttoAmortizationDetails</Role>
      <ShortName>Goodwill and Intangible Assets - Summary of Intangible Assets Subject to Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>0000073 - Disclosure - Goodwill and Intangible Assets - Future Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/GoodwillandIntangibleAssetsFutureAmortizationDetails</Role>
      <ShortName>Goodwill and Intangible Assets - Future Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>0000074 - Disclosure - Deposits - Maturities of Time Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/DepositsMaturitiesofTimeDepositsDetails</Role>
      <ShortName>Deposits - Maturities of Time Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>0000075 - Disclosure - Deposits - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/DepositsNarrativeDetails</Role>
      <ShortName>Deposits - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>0000076 - Disclosure - Short-term Borrowings - Federal Funds Purchased and Short-term Borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/ShorttermBorrowingsFederalFundsPurchasedandShorttermBorrowingsDetails</Role>
      <ShortName>Short-term Borrowings - Federal Funds Purchased and Short-term Borrowings (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>0000077 - Disclosure - Other Borrowed Funds - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherBorrowedFundsNarrativeDetails</Role>
      <ShortName>Other Borrowed Funds - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>0000078 - Disclosure - Other Borrowed Funds - Federal Home Loan Bank Advances (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherBorrowedFundsFederalHomeLoanBankAdvancesDetails</Role>
      <ShortName>Other Borrowed Funds - Federal Home Loan Bank Advances (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>0000079 - Disclosure - Income Taxes - Provision for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxesProvisionforIncomeTaxesDetails</Role>
      <ShortName>Income Taxes - Provision for Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>0000080 - Disclosure - Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxesSummaryofDeferredTaxAssetsandLiabilitiesDetails</Role>
      <ShortName>Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>0000081 - Disclosure - Income Taxes - Federal Income Tax Reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxesFederalIncomeTaxReconciliationDetails</Role>
      <ShortName>Income Taxes - Federal Income Tax Reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>0000082 - Disclosure - Income Taxes - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>0000083 - Disclosure - Employee Benefits - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefitsNarrativeDetails</Role>
      <ShortName>Employee Benefits - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>0000084 - Disclosure - Employee Benefits - Restricted Stock Awards and Stock Option Grant (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefitsRestrictedStockAwardsandStockOptionGrantDetails</Role>
      <ShortName>Employee Benefits - Restricted Stock Awards and Stock Option Grant (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>0000085 - Disclosure - Employee Benefits - Stock Option Plan Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefitsStockOptionPlanActivityDetails</Role>
      <ShortName>Employee Benefits - Stock Option Plan Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>0000086 - Disclosure - Employee Benefits - Restricted Stock Award Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/EmployeeBenefitsRestrictedStockAwardActivityDetails</Role>
      <ShortName>Employee Benefits - Restricted Stock Award Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>0000087 - Disclosure - Commitments and Contingent Liabilities - Unused and Available Credit Balances of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CommitmentsandContingentLiabilitiesUnusedandAvailableCreditBalancesofFinancialInstrumentsDetails</Role>
      <ShortName>Commitments and Contingent Liabilities - Unused and Available Credit Balances of Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>0000088 - Disclosure - Commitments and Contingent Liabilities - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CommitmentsandContingentLiabilitiesNarrativeDetails</Role>
      <ShortName>Commitments and Contingent Liabilities - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>0000089 - Disclosure - Stockholders' Equity and Regulatory Capital - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/StockholdersEquityandRegulatoryCapitalNarrativeDetails</Role>
      <ShortName>Stockholders' Equity and Regulatory Capital - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>0000090 - Disclosure - Stockholders' Equity and Regulatory Capital - Summary of Capital Ratios (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/StockholdersEquityandRegulatoryCapitalSummaryofCapitalRatiosDetails</Role>
      <ShortName>Stockholders' Equity and Regulatory Capital - Summary of Capital Ratios (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>0000091 - Disclosure - Operating Leases - Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OperatingLeasesOperatingLeasesDetails</Role>
      <ShortName>Operating Leases - Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>0000092 - Disclosure - Operating Leases - Maturity of Operating Lease (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OperatingLeasesMaturityofOperatingLeaseDetails</Role>
      <ShortName>Operating Leases - Maturity of Operating Lease (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>0000093 - Disclosure - Operating Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OperatingLeasesNarrativeDetails</Role>
      <ShortName>Operating Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>0000094 - Disclosure - Mortgage Servicing Rights (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/MortgageServicingRightsDetails</Role>
      <ShortName>Mortgage Servicing Rights (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/MortgageServicingRightsTables</ParentRole>
      <Position>94</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>0000095 - Disclosure - Fair Value Disclosure - Assets and Liabilities Reported Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosureAssetsandLiabilitiesReportedFairValueDetails</Role>
      <ShortName>Fair Value Disclosure - Assets and Liabilities Reported Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>0000096 - Disclosure - Fair Value Disclosure - Significant Unobservable Inputs Used in the Fair Value Measurements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosureSignificantUnobservableInputsUsedintheFairValueMeasurementsDetails</Role>
      <ShortName>Fair Value Disclosure - Significant Unobservable Inputs Used in the Fair Value Measurements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>0000097 - Disclosure - Fair Value Disclosure - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosureNarrativeDetails</Role>
      <ShortName>Fair Value Disclosure - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>0000098 - Disclosure - Fair Value Disclosure - Estimated Fair Value of the Company's Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/FairValueDisclosureEstimatedFairValueoftheCompanysFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value Disclosure - Estimated Fair Value of the Company's Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>0000099 - Disclosure - Other Noninterest Expense - Components of Other Noninterest Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/OtherNoninterestExpenseComponentsofOtherNoninterestExpenseDetails</Role>
      <ShortName>Other Noninterest Expense - Components of Other Noninterest Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>0000100 - Disclosure - Condensed Financial Statements of Parent Company - Statement of Financial Condition (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompanyStatementofFinancialConditionDetails</Role>
      <ShortName>Condensed Financial Statements of Parent Company - Statement of Financial Condition (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>0000101 - Disclosure - Condensed Financial Statements of Parent Company - Statement of Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompanyStatementofIncomeDetails</Role>
      <ShortName>Condensed Financial Statements of Parent Company - Statement of Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>0000102 - Disclosure - Condensed Financial Statements of Parent Company - Statement of Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/CondensedFinancialStatementsofParentCompanyStatementofCashFlowsDetails</Role>
      <ShortName>Condensed Financial Statements of Parent Company - Statement of Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="cbfv-20221231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>0000103 - Disclosure - Segment Reporting and Related Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.communitybank.tv/role/SegmentReportingandRelatedInformationDetails</Role>
      <ShortName>Segment Reporting and Related Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.communitybank.tv/role/SegmentReportingandRelatedInformationTables</ParentRole>
      <Position>103</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: 7 fact(s) appearing in ix:hidden were eligible for transformation: cbfv:ShareBasedCompensationArrangementByShareBasedPaymentAwardShareLimitRatio, us-gaap:PropertyPlantAndEquipmentUsefulLife, us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1 -  cbfv-20221231.htm 4</Log>
  </Logs>
  <InputFiles>
    <File doctype="10-K" original="cbfv-20221231.htm">cbfv-20221231.htm</File>
    <File>cbfv-20221231.xsd</File>
    <File>cbfv-20221231_cal.xml</File>
    <File>cbfv-20221231_def.xml</File>
    <File>cbfv-20221231_lab.xml</File>
    <File>cbfv-20221231_pre.xml</File>
    <File>cbfv-20221231xex1018xemplo.htm</File>
    <File>cbfv-20221231xex21subsidia.htm</File>
    <File>cbfv-20221231xex231consent.htm</File>
    <File>cbfv-20221231xex311ceocert.htm</File>
    <File>cbfv-20221231xex312cfocert.htm</File>
    <File>cbfv-20221231xex321ceoandc.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>cbfv-20221231_g1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="3">http://fasb.org/srt/2022</BaseTaxonomy>
    <BaseTaxonomy items="1779">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>
