<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>616</ContextCount>
  <ElementCount>355</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>91</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>75000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>75010 - Statement - Consolidated Balance Sheets (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedBalanceSheetsUnaudited</Role>
      <ShortName>Consolidated Balance Sheets (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>75020 - Statement - Consolidated Balance Sheets (Parenthetical) (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedBalanceSheetsParentheticalUnaudited</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical) (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>75030 - Statement - Consolidated Statements of Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedStatementsOfIncomeUnaudited</Role>
      <ShortName>Consolidated Statements of Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>75040 - Statement - Consolidated Statements of Comprehensive Income (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncomeUnaudited</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>75050 - Statement - Consolidated Statements of Stockholders' Equity (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquityUnaudited</Role>
      <ShortName>Consolidated Statements of Stockholders' Equity (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>75060 - Statement - Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/StatementConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.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>8</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.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>9</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Nature of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureNatureOfBusiness</Role>
      <ShortName>Nature of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Investment Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecurities1</Role>
      <ShortName>Investment Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Loans and Allowance for Credit Losses - Loans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoans</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Operating Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeases</Role>
      <ShortName>Operating Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Loan Servicing Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssets</Role>
      <ShortName>Loan Servicing Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDeposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Subordinated Debt, Other Borrowings, and Available Lines of Credit</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSubordinatedDebtOtherBorrowingsAndAvailableLinesOfCredit</Role>
      <ShortName>Subordinated Debt, Other Borrowings, and Available Lines of Credit</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Stockholders' Equity and Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShare</Role>
      <ShortName>Stockholders' Equity and Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Regulatory Capital Requirements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirements</Role>
      <ShortName>Regulatory Capital Requirements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995545 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Nature of Business (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureNatureOfBusinessPolicies</Role>
      <ShortName>Nature of Business (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Investment Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesTables</Role>
      <ShortName>Investment Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecurities1</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Loans and Allowance for Credit Losses - Loans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansTables</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoans</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Operating Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeasesTables</Role>
      <ShortName>Operating Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeases</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Loan Servicing Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssetsTables</Role>
      <ShortName>Loan Servicing Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssets</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDeposits</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Stockholders' Equity and Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShareTables</Role>
      <ShortName>Stockholders' Equity and Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShare</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Regulatory Capital Requirements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirementsTables</Role>
      <ShortName>Regulatory Capital Requirements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirements</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurements</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReporting</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Nature of Business (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureNatureOfBusinessAdditionalInformationDetails</Role>
      <ShortName>Nature of Business (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureNatureOfBusinessPolicies</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Investment Securities (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesAdditionalInformationDetails</Role>
      <ShortName>Investment Securities (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Investment Securities - Summary of amortized cost, unrealized gains and losses, allowance for credit losses, and estimated fair values of investment securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesSummaryOfAmortizedCostUnrealizedGainsAndLossesAllowanceForCreditLossesAndEstimatedFairValuesOfInvestmentSec</Role>
      <ShortName>Investment Securities - Summary of amortized cost, unrealized gains and losses, allowance for credit losses, and estimated fair values of investment securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Investment Securities - Summary of maturity distribution of investment securities at amortized cost and fair value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesSummaryOfMaturityDistributionOfInvestmentSecuritiesAtAmortizedCostAndFairValueDetails</Role>
      <ShortName>Investment Securities - Summary of maturity distribution of investment securities at amortized cost and fair value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Investment Securities - Summary of gross unrealized losses and fair value of debt security investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureInvestmentSecuritiesSummaryOfGrossUnrealizedLossesAndFairValueOfDebtSecurityInvestmentsDetails</Role>
      <ShortName>Investment Securities - Summary of gross unrealized losses and fair value of debt security investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Loans and Allowance for Credit Losses - Loans - The Principal Balances of Loans Held for Sale are Listed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansThePrincipalBalancesOfLoansHeldForSaleAreListedDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - The Principal Balances of Loans Held for Sale are Listed (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Loans and Allowance for Credit Losses - Loans - The Amortized Cost of Loans Held for Investment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansTheAmortizedCostOfLoansHeldForInvestmentDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - The Amortized Cost of Loans Held for Investment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Loans and Allowance for Credit Losses - Loans (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansAdditionalInformationDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Loans and Allowance for Credit Losses - Loans - Summary of Past Due and Non-accrual Loans Portfolio Summarized by the Past Due Status (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansSummaryOfPastDueAndNonaccrualLoansPortfolioSummarizedByThePastDueStatusDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - Summary of Past Due and Non-accrual Loans Portfolio Summarized by the Past Due Status (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Loans and Allowance for Credit Losses - Summary of Amortized Cost of Loans Receivable by Year Of Origination Risk Grade Within Each Portfolio (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesSummaryOfAmortizedCostOfLoansReceivableByYearOfOriginationRiskGradeWithinEachPortfolioDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Summary of Amortized Cost of Loans Receivable by Year Of Origination Risk Grade Within Each Portfolio (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Loans and Allowance for Credit Losses - Summary of Amortized Cost Basis Of Collateral-Dependent Loans By Collateral Type (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesSummaryOfAmortizedCostBasisOfCollateraldependentLoansByCollateralTypeDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Summary of Amortized Cost Basis Of Collateral-Dependent Loans By Collateral Type (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Loans and Allowance for Credit Losses - Loans - Summary of the amortized cost basis of collateral-dependent loans by loan portfolio segment and the related allowance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansSummaryOfTheAmortizedCostBasisOfCollateraldependentLoansByLoanPortfolioSegmentAndTheRel</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - Summary of the amortized cost basis of collateral-dependent loans by loan portfolio segment and the related allowance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Loans and Allowance for Credit Losses - Loans - Schedule of Portfolio Segment, the Changes in the Allowance for Credit Losses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansScheduleOfPortfolioSegmentTheChangesInTheAllowanceForCreditLossesDetails</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - Schedule of Portfolio Segment, the Changes in the Allowance for Credit Losses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Loans and Allowance for Credit Losses - Loans - Summary of the amortized cost basis of loans held for investment that were modified during the period for borrowers experiencing financial difficulty by loan portfolio segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoansAndAllowanceForCreditLossesLoansSummaryOfTheAmortizedCostBasisOfLoansHeldForInvestmentThatWereModifiedDuringThePeriod</Role>
      <ShortName>Loans and Allowance for Credit Losses - Loans - Summary of the amortized cost basis of loans held for investment that were modified during the period for borrowers experiencing financial difficulty by loan portfolio segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Operating Leases (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeasesAdditionalInformationDetails</Role>
      <ShortName>Operating Leases (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeasesTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995845 - Disclosure - Operating Leases - Schedule of Operating Lease Right-of-Use Asset and Related Lease Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeasesScheduleOfOperatingLeaseRightofuseAssetAndRelatedLeaseLiabilityDetails</Role>
      <ShortName>Operating Leases - Schedule of Operating Lease Right-of-Use Asset and Related Lease Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995855 - Disclosure - Operating Leases - Schedule of Future Minimum Rental Payments for Operating Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureOperatingLeasesScheduleOfFutureMinimumRentalPaymentsForOperatingLeasesDetails</Role>
      <ShortName>Operating Leases - Schedule of Future Minimum Rental Payments for Operating Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Loan Servicing Assets (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssetsAdditionalInformationDetails</Role>
      <ShortName>Loan Servicing Assets (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssetsTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995875 - Disclosure - Loan Servicing Assets - Schedule of Reconciliation of Loan Servicing Rights (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureLoanServicingAssetsScheduleOfReconciliationOfLoanServicingRightsDetails</Role>
      <ShortName>Loan Servicing Assets - Schedule of Reconciliation of Loan Servicing Rights (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995885 - Disclosure - Deposits - Scheduled Maturities of Time Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDepositsScheduledMaturitiesOfTimeDepositsDetails</Role>
      <ShortName>Deposits - Scheduled Maturities of Time Deposits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Deposits (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDepositsAdditionalInformationDetails</Role>
      <ShortName>Deposits (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureDepositsTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995905 - Disclosure - Subordinated Debt, Other Borrowings, and Available Lines of Credit (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSubordinatedDebtOtherBorrowingsAndAvailableLinesOfCreditAdditionalInformationDetails</Role>
      <ShortName>Subordinated Debt, Other Borrowings, and Available Lines of Credit (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSubordinatedDebtOtherBorrowingsAndAvailableLinesOfCredit</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995915 - Disclosure - Stockholders' Equity and Earnings Per Share (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShareAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity and Earnings Per Share (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShareTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Stockholders' Equity and Earnings Per Share - Schedule of earnings per share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureStockholdersEquityAndEarningsPerShareScheduleOfEarningsPerShareDetails</Role>
      <ShortName>Stockholders' Equity and Earnings Per Share - Schedule of earnings per share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Regulatory Capital Requirements - Summary of the main components and requirements of the CBLR (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirementsSummaryOfTheMainComponentsAndRequirementsOfTheCblrDetails</Role>
      <ShortName>Regulatory Capital Requirements - Summary of the main components and requirements of the CBLR (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Regulatory Capital Requirements - Summary of Actual and required capital amounts and ratios for the Bank (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirementsSummaryOfActualAndRequiredCapitalAmountsAndRatiosForTheBankDetails</Role>
      <ShortName>Regulatory Capital Requirements - Summary of Actual and required capital amounts and ratios for the Bank (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>995955 - Disclosure - Regulatory Capital Requirements (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirementsAdditionalInformationDetails</Role>
      <ShortName>Regulatory Capital Requirements (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureRegulatoryCapitalRequirementsTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>995965 - Disclosure - Commitments and Contingencies - Summary of the contractual amounts of the Company's exposure to off-balance-sheet risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesSummaryOfTheContractualAmountsOfTheCompanysExposureToOffbalancesheetRiskDetails</Role>
      <ShortName>Commitments and Contingencies - Summary of the contractual amounts of the Company's exposure to off-balance-sheet risk (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>995975 - Disclosure - Commitments and Contingencies - Summary of the contractual amounts of the Company's exposure to off-balance-sheet risk (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesSummaryOfTheContractualAmountsOfTheCompanysExposureToOffbalancesheetRiskParentheticalDetails</Role>
      <ShortName>Commitments and Contingencies - Summary of the contractual amounts of the Company's exposure to off-balance-sheet risk (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>995985 - Disclosure - Commitments and Contingencies - Dispersion of Loan Principal Balances and Related Commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesDispersionOfLoanPrincipalBalancesAndRelatedCommitmentsDetails</Role>
      <ShortName>Commitments and Contingencies - Dispersion of Loan Principal Balances and Related Commitments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>995995 - Disclosure - Commitments and Contingencies (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetails</Role>
      <ShortName>Commitments and Contingencies (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureCommitmentsAndContingenciesTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Income Taxes (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetails</Role>
      <ShortName>Income Taxes (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureIncomeTaxes</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Fair Value Measurements - Schedule of balance of financial assets measured at fair value on Recurring and nonrecurring Basis Segregated by Level of Valuation Inputs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfBalanceOfFinancialAssetsMeasuredAtFairValueOnRecurringAndNonrecurringBasisSegregatedByLevelOfV</Role>
      <ShortName>Fair Value Measurements - Schedule of balance of financial assets measured at fair value on Recurring and nonrecurring Basis Segregated by Level of Valuation Inputs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>996035 - Disclosure - Fair Value Measurements - Schedule of Quantitative Information about assets measured at fair value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfQuantitativeInformationAboutAssetsMeasuredAtFairValueDetails</Role>
      <ShortName>Fair Value Measurements - Schedule of Quantitative Information about assets measured at fair value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>996045 - Disclosure - Fair Value Measurements - Schedule of Carrying Amounts and Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfCarryingAmountsAndFairValueOfFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value Measurements - Schedule of Carrying Amounts and Fair Value of Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>996055 - Disclosure - Segment Reporting (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReportingAdditionalInformationDetails</Role>
      <ShortName>Segment Reporting (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReportingTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="gbfh-20260630.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>996065 - Disclosure - Segment Reporting - Schedule Of Segment Reporting Information Reviewed By Management (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gbankfinancialholdings.com/20260630/taxonomy/role/DisclosureSegmentReportingScheduleOfSegmentReportingInformationReviewedByManagementDetails</Role>
      <ShortName>Segment Reporting - Schedule Of Segment Reporting Information Reviewed By Management (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="gbfh-20260630.htm">gbfh-20260630.htm</File>
    <File>gbfh-20260630.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="1849">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="9">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
