<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>808</ContextCount>
  <ElementCount>630</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>112</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>995200090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>995200100 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>995200105 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>995200200 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>995200300 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>995200400 - Statement - Consolidated Statement of Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementOfStockholdersEquity</Role>
      <ShortName>Consolidated Statement of Stockholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>995200405 - Statement - Consolidated Statements of Stockholders' Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementsOfStockholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>995200500 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995200505 - Statement - Consolidated Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/StatementConsolidatedStatementsOfCashFlowsParenthetical</Role>
      <ShortName>Consolidated Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995210101 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995210201 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995210301 - Disclosure - Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecurities</Role>
      <ShortName>Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995210401 - Disclosure - Loans and Allowance for Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLosses</Role>
      <ShortName>Loans and Allowance for Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995210501 - Disclosure - Related Party Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureRelatedPartyMatters</Role>
      <ShortName>Related Party Matters</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995210601 - Disclosure - Mortgage Servicing Rights</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureMortgageServicingRights</Role>
      <ShortName>Mortgage Servicing Rights</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995210701 - Disclosure - Premises and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosurePremisesAndEquipment</Role>
      <ShortName>Premises and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995210801 - Disclosure - Other Real Estate Owned</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureOtherRealEstateOwned</Role>
      <ShortName>Other Real Estate Owned</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995210901 - Disclosure - Investment in Minority-owned Subsidiaries</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureInvestmentInMinorityOwnedSubsidiaries</Role>
      <ShortName>Investment in Minority-owned Subsidiaries</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995211001 - Disclosure - Core Deposit Intangibles</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCoreDepositIntangibles</Role>
      <ShortName>Core Deposit Intangibles</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995211101 - Disclosure - Goodwill</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureGoodwill</Role>
      <ShortName>Goodwill</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995211201 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureDeposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995211301 - Disclosure - Securities Sold Under Repurchase Agreement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesSoldUnderRepurchaseAgreement</Role>
      <ShortName>Securities Sold Under Repurchase Agreement</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995211401 - Disclosure - Notes Payable</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureNotesPayable</Role>
      <ShortName>Notes Payable</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995211501 - Disclosure - Subordinated Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSubordinatedDebt</Role>
      <ShortName>Subordinated Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995211601 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995211701 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlans</Role>
      <ShortName>Employee Benefit Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995211801 - Disclosure - Stockholders' Equity and Regulatory Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureStockholdersEquityAndRegulatoryMatters</Role>
      <ShortName>Stockholders' Equity and Regulatory Matters</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995211901 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995212001 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995212101 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995212201 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995212301 - Disclosure - Parent Company Only Financial Statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatements</Role>
      <ShortName>Parent Company Only Financial Statements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995212401 - Disclosure - Earnings Per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEarningsPerCommonShare</Role>
      <ShortName>Earnings Per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995212501 - Disclosure - Subsequent Merger Transaction</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSubsequentMergerTransaction</Role>
      <ShortName>Subsequent Merger Transaction</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995447 - Disclosure - Insider Trading Policies and Procedures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingPoliciesProc</Role>
      <ShortName>Insider Trading Policies and Procedures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995550 - Disclosure - Cybersecurity Risk Management and Strategy Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/cyd/role/CybersecurityRiskManagementAndStrategyDisclosure</Role>
      <ShortName>Cybersecurity Risk Management and Strategy Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>99920102 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>99930103 - Disclosure - Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>99930203 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureAcquisitions</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>99930303 - Disclosure - Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesTables</Role>
      <ShortName>Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSecurities</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>99930403 - Disclosure - Loans and Allowance for Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesTables</Role>
      <ShortName>Loans and Allowance for Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLosses</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>99930503 - Disclosure - Related Party Matters (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureRelatedPartyMattersTables</Role>
      <ShortName>Related Party Matters (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureRelatedPartyMatters</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>99930603 - Disclosure - Mortgage Servicing Rights (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureMortgageServicingRightsTables</Role>
      <ShortName>Mortgage Servicing Rights (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureMortgageServicingRights</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>99930703 - Disclosure - Premises and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosurePremisesAndEquipmentTables</Role>
      <ShortName>Premises and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosurePremisesAndEquipment</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>99930803 - Disclosure - Other Real Estate Owned (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureOtherRealEstateOwnedTables</Role>
      <ShortName>Other Real Estate Owned (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureOtherRealEstateOwned</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>99931003 - Disclosure - Core Deposit Intangibles (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCoreDepositIntangiblesTables</Role>
      <ShortName>Core Deposit Intangibles (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureCoreDepositIntangibles</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>99931203 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureDepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureDeposits</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>99931303 - Disclosure - Securities Sold Under Repurchase Agreements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesSoldUnderRepurchaseAgreementsTables</Role>
      <ShortName>Securities Sold Under Repurchase Agreements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSecuritiesSoldUnderRepurchaseAgreement</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>99931403 - Disclosure - Notes Payable (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureNotesPayableTables</Role>
      <ShortName>Notes Payable (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureNotesPayable</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>99931603 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>99931703 - Disclosure - Employee Benefit Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlansTables</Role>
      <ShortName>Employee Benefit Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlans</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>99931803 - Disclosure - Stockholders' Equity and Regulatory Matters (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureStockholdersEquityAndRegulatoryMattersTables</Role>
      <ShortName>Stockholders' Equity and Regulatory Matters (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureStockholdersEquityAndRegulatoryMatters</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>99932003 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>99932103 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureLeases</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>99932203 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstruments</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>99932303 - Disclosure - Parent Company Only Financial Statements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatementsTables</Role>
      <ShortName>Parent Company Only Financial Statements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatements</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>99932403 - Disclosure - Earnings Per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEarningsPerCommonShareTables</Role>
      <ShortName>Earnings Per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureEarningsPerCommonShare</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>99940101 - Disclosure - Summary of Significant Accounting Policies - Principles of Consolidation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPrinciplesOfConsolidationDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Principles of Consolidation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>99940102 - Disclosure - Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesCashAndCashEquivalentsDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>99940103 - Disclosure - Summary of Significant Accounting Policies - Loans and Related Interest Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesLoansAndRelatedInterestIncomeDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Loans and Related Interest Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>99940104 - Disclosure - Summary of Significant Accounting Policies - Premises and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPremisesAndEquipmentDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Premises and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>99940105 - Disclosure - Summary of Significant Accounting Policies - Intangible Assets and Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesIntangibleAssetsAndGoodwillDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Intangible Assets and Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>99940106 - Disclosure - Summary of Significant Accounting Policies - Earnings Per Share Computations and Operating Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSummaryOfSignificantAccountingPoliciesEarningsPerShareComputationsAndOperatingSegmentsDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Earnings Per Share Computations and Operating Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>99940201 - Disclosure - Acquisitions - Hometown (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureAcquisitionsHometownDetails</Role>
      <ShortName>Acquisitions - Hometown (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>99940202 - Disclosure - Acquisitions - Hometown - Fair value of assets acquired and liabilities assumed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureAcquisitionsHometownFairValueOfAssetsAcquiredAndLiabilitiesAssumedDetails</Role>
      <ShortName>Acquisitions - Hometown - Fair value of assets acquired and liabilities assumed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>99940203 - Disclosure - Acquisitions - Hometown - Loans purchased through acquisition (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureAcquisitionsHometownLoansPurchasedThroughAcquisitionDetails</Role>
      <ShortName>Acquisitions - Hometown - Loans purchased through acquisition (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>99940301 - Disclosure - Securities - Summary of securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesSummaryOfSecuritiesDetails</Role>
      <ShortName>Securities - Summary of securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>99940302 - Disclosure - Securities - Fair value and gross unrealized losses of securities with unrealized losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesFairValueAndGrossUnrealizedLossesOfSecuritiesWithUnrealizedLossesDetails</Role>
      <ShortName>Securities - Fair value and gross unrealized losses of securities with unrealized losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>99940303 - Disclosure - Securities - Amortized cost and estimated fair value of securities by contractual maturity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesAmortizedCostAndEstimatedFairValueOfSecuritiesByContractualMaturityDetails</Role>
      <ShortName>Securities - Amortized cost and estimated fair value of securities by contractual maturity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>99940304 - Disclosure - Securities - Sales of securities available for sate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesSalesOfSecuritiesAvailableForSateDetails</Role>
      <ShortName>Securities - Sales of securities available for sate (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>99940401 - Disclosure - Loans and Allowance for Credit Losses - Composition of loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesCompositionOfLoansDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Composition of loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>99940402 - Disclosure - Loans and Allowance for Credit Losses - Qualitative Factors (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesQualitativeFactorsDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Qualitative Factors (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>99940403 - Disclosure - Loans and Allowance for Credit Losses - Activity in the ACL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesActivityInAclDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Activity in the ACL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>99940404 - Disclosure - Loans and Allowance for Credit Losses - Provisions for credit losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesProvisionsForCreditLossesDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Provisions for credit losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>99940405 - Disclosure - Loans and Allowance for Credit Losses - Past due and non-accrual loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesPastDueAndNonAccrualLoansDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Past due and non-accrual loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>99940406 - Disclosure - Loans and Allowance for Credit Losses - Collateral dependent loans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesCollateralDependentLoansDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Collateral dependent loans (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>99940407 - Disclosure - Loans and Allowance for Credit Losses - Total loans by risk ratings and year of origination (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLoansAndAllowanceForCreditLossesTotalLoansByRiskRatingsAndYearOfOriginationDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Total loans by risk ratings and year of origination (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>99940501 - Disclosure - Related Party Matters (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureRelatedPartyMattersDetails</Role>
      <ShortName>Related Party Matters (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureRelatedPartyMattersTables</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>99940601 - Disclosure - Mortgage Servicing Rights (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureMortgageServicingRightsDetails</Role>
      <ShortName>Mortgage Servicing Rights (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureMortgageServicingRightsTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>99940701 - Disclosure - Premises and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosurePremisesAndEquipmentDetails</Role>
      <ShortName>Premises and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosurePremisesAndEquipmentTables</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>99940801 - Disclosure - Other Real Estate Owned - Changes in OREO (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureOtherRealEstateOwnedChangesInOreoDetails</Role>
      <ShortName>Other Real Estate Owned - Changes in OREO (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>99940802 - Disclosure - Other Real Estate Owned - Activity in the valuation allowance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureOtherRealEstateOwnedActivityInValuationAllowanceDetails</Role>
      <ShortName>Other Real Estate Owned - Activity in the valuation allowance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>99940901 - Disclosure - Investment in Minority-owned Subsidiaries (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureInvestmentInMinorityOwnedSubsidiariesDetails</Role>
      <ShortName>Investment in Minority-owned Subsidiaries (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureInvestmentInMinorityOwnedSubsidiaries</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>99941001 - Disclosure - Core Deposit Intangibles - Gross carrying amount and accumulated amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCoreDepositIntangiblesGrossCarryingAmountAndAccumulatedAmortizationDetails</Role>
      <ShortName>Core Deposit Intangibles - Gross carrying amount and accumulated amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>99941002 - Disclosure - Core Deposit Intangibles - Estimated future amortization expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCoreDepositIntangiblesEstimatedFutureAmortizationExpenseDetails</Role>
      <ShortName>Core Deposit Intangibles - Estimated future amortization expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>99941101 - Disclosure - Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureGoodwillDetails</Role>
      <ShortName>Goodwill (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureGoodwill</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>99941201 - Disclosure - Deposits - Composition of deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureDepositsCompositionOfDepositsDetails</Role>
      <ShortName>Deposits - Composition of deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>99941202 - Disclosure - Deposits - Maturities of time deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureDepositsMaturitiesOfTimeDepositsDetails</Role>
      <ShortName>Deposits - Maturities of time deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>99941301 - Disclosure - Securities Sold Under Repurchase Agreements (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSecuritiesSoldUnderRepurchaseAgreementsDetails</Role>
      <ShortName>Securities Sold Under Repurchase Agreements (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSecuritiesSoldUnderRepurchaseAgreementsTables</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>99941401 - Disclosure - Notes Payable - FHLB advances (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureNotesPayableFhlbAdvancesDetails</Role>
      <ShortName>Notes Payable - FHLB advances (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>99941402 - Disclosure - Notes Payable - Future maturities (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureNotesPayableFutureMaturitiesDetails</Role>
      <ShortName>Notes Payable - Future maturities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>99941403 - Disclosure - Notes Payable - Additional Information (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureNotesPayableAdditionalInformationDetails</Role>
      <ShortName>Notes Payable - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>99941501 - Disclosure - Subordinated Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSubordinatedDebtDetails</Role>
      <ShortName>Subordinated Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSubordinatedDebt</ParentRole>
      <Position>95</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>99941601 - Disclosure - Income Taxes - Components of the provision for income taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureIncomeTaxesComponentsOfProvisionForIncomeTaxesDetails</Role>
      <ShortName>Income Taxes - Components of the provision for income taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>99941602 - Disclosure - Income Taxes - Tax rate reconciliation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureIncomeTaxesTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes - Tax rate reconciliation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>99941603 - Disclosure - Income Taxes - Deferred tax (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureIncomeTaxesDeferredTaxDetails</Role>
      <ShortName>Income Taxes - Deferred tax (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>99941701 - Disclosure - Employee Benefit Plans - Employee Stock Ownership Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlansEmployeeStockOwnershipPlanDetails</Role>
      <ShortName>Employee Benefit Plans - Employee Stock Ownership Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>99941702 - Disclosure - Employee Benefit Plans - Share-based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlansShareBasedCompensationDetails</Role>
      <ShortName>Employee Benefit Plans - Share-based Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>99941703 - Disclosure - Employee Benefit Plans - Deferred Compensation Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEmployeeBenefitPlansDeferredCompensationPlanDetails</Role>
      <ShortName>Employee Benefit Plans - Deferred Compensation Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>99941801 - Disclosure - Stockholders' Equity and Regulatory Matters (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureStockholdersEquityAndRegulatoryMattersDetails</Role>
      <ShortName>Stockholders' Equity and Regulatory Matters (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureStockholdersEquityAndRegulatoryMattersTables</ParentRole>
      <Position>102</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>99942001 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureCommitmentsAndContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureCommitmentsAndContingenciesTables</ParentRole>
      <Position>103</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>99942101 - Disclosure - Leases - Operating leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLeasesOperatingLeasesDetails</Role>
      <ShortName>Leases - Operating leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>99942102 - Disclosure - Leases - Maturity analysis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureLeasesMaturityAnalysisDetails</Role>
      <ShortName>Leases - Maturity analysis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>99942201 - Disclosure - Fair Value of Financial Instruments - Fair value of assets measured on a recurring basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstrumentsFairValueOfAssetsMeasuredOnRecurringBasisDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Fair value of assets measured on a recurring basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>99942202 - Disclosure - Fair Value of Financial Instruments - Fair value of assets measured on a non-recurring basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstrumentsFairValueOfAssetsMeasuredOnNonRecurringBasisDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Fair value of assets measured on a non-recurring basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>99942203 - Disclosure - Fair Value of Financial Instruments - Fair value measurement on inputs and valuation techniques (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstrumentsFairValueMeasurementOnInputsAndValuationTechniquesDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Fair value measurement on inputs and valuation techniques (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>99942204 - Disclosure - Fair Value of Financial Instruments - Carrying value and estimated fair value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureFairValueOfFinancialInstrumentsCarryingValueAndEstimatedFairValueDetails</Role>
      <ShortName>Fair Value of Financial Instruments - Carrying value and estimated fair value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>99942301 - Disclosure - Parent Company Only Financial Statements - Balance Sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatementsBalanceSheetsDetails</Role>
      <ShortName>Parent Company Only Financial Statements - Balance Sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>99942302 - Disclosure - Parent Company Only Financial Statements - Statements of Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatementsStatementsOfIncomeDetails</Role>
      <ShortName>Parent Company Only Financial Statements - Statements of Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>99942303 - Disclosure - Parent Company Only Financial Statements - Statements of Cash Flows (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureParentCompanyOnlyFinancialStatementsStatementsOfCashFlowsDetails</Role>
      <ShortName>Parent Company Only Financial Statements - Statements of Cash Flows (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>99942401 - Disclosure - Earnings Per Common Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureEarningsPerCommonShareDetails</Role>
      <ShortName>Earnings Per Common Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureEarningsPerCommonShareTables</ParentRole>
      <Position>113</Position>
    </Report>
    <Report instance="bfc-20251231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>99942501 - Disclosure - Subsequent Merger Transaction (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.bankfirstnational.com/role/DisclosureSubsequentMergerTransactionDetails</Role>
      <ShortName>Subsequent Merger Transaction (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.bankfirstnational.com/role/DisclosureSubsequentMergerTransaction</ParentRole>
      <Position>114</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>bfc-20251231.xsd</File>
    <File>bfc-20251231_cal.xml</File>
    <File>bfc-20251231_def.xml</File>
    <File>bfc-20251231_lab.xml</File>
    <File>bfc-20251231_pre.xml</File>
    <File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="bfc-20251231x10k.htm">bfc-20251231x10k.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>bfc-20251231x10k007.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="3">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="2003">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="15">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="38">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="6">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
