<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>1150</ContextCount>
  <ElementCount>776</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>175</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - DOCUMENT AND ENTITY INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DOCUMENTANDENTITYINFORMATION</Role>
      <ShortName>DOCUMENT AND ENTITY INFORMATION</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - Document - Audit Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/AuditInformation</Role>
      <ShortName>Audit Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952151 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952152 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952153 - Statement - CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDSTATEMENTSOFINCOME</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952154 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOME</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952155 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMEParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952156 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDSTATEMENTSOFCHANGESINSTOCKHOLDERSEQUITY</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952157 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/SummaryofSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - Variable Interest Entities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/VariableInterestEntities</Role>
      <ShortName>Variable Interest Entities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - Debt Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecurities</Role>
      <ShortName>Debt Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - Loans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/Loans</Role>
      <ShortName>Loans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - Loans And The Allowance For Credit Losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLosses</Role>
      <ShortName>Loans And The Allowance For Credit Losses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - Servicing of Financial Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssets</Role>
      <ShortName>Servicing of Financial Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - Other Earning Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherEarningAssets</Role>
      <ShortName>Other Earning Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - Premises and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/PremisesandEquipment</Role>
      <ShortName>Premises and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/Deposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - Borrowed Funds</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BorrowedFunds</Role>
      <ShortName>Borrowed Funds</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9952169 - Disclosure - Regulatory Capital Requirements and Restrictions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictions</Role>
      <ShortName>Regulatory Capital Requirements and Restrictions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9952170 - Disclosure - Leases (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.regions.com/role/LeasesNotes</Role>
      <ShortName>Leases (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9952171 - Disclosure - Shareholders' Equity and Accumulated Other Comprehensive Income (Loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLoss</Role>
      <ShortName>Shareholders' Equity and Accumulated Other Comprehensive Income (Loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9952172 - Disclosure - Earnings Per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EarningsPerCommonShare</Role>
      <ShortName>Earnings Per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9952173 - Disclosure - Share-Based Payments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareBasedPayments</Role>
      <ShortName>Share-Based Payments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9952174 - Disclosure - Employee Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlans</Role>
      <ShortName>Employee Benefit Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9952175 - Disclosure - Other Non-Interest Income and Expense</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherNonInterestIncomeandExpense</Role>
      <ShortName>Other Non-Interest Income and Expense</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9952176 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9952177 - Disclosure - Derivative Financial Instruments and Hedging Activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsandHedgingActivities</Role>
      <ShortName>Derivative Financial Instruments and Hedging Activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9952178 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9952179 - Disclosure - Business Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BusinessSegmentInformation</Role>
      <ShortName>Business Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9952180 - Disclosure - Commitments, Contingencies and Guarantees</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CommitmentsContingenciesandGuarantees</Role>
      <ShortName>Commitments, Contingencies and Guarantees</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9952181 - Disclosure - Parent Company Only Financial Statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ParentCompanyOnlyFinancialStatements</Role>
      <ShortName>Parent Company Only Financial Statements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.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>34</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.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>35</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.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>36</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.regions.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - Summary of Significant Accounting Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesTables</Role>
      <ShortName>Summary of Significant Accounting Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - Variable Interest Entities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/VariableInterestEntitiesTables</Role>
      <ShortName>Variable Interest Entities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/VariableInterestEntities</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - Debt Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesTables</Role>
      <ShortName>Debt Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecurities</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - Loans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansTables</Role>
      <ShortName>Loans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/Loans</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - Loans And The Allowance For Credit Losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLosses</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - Servicing of Financial Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssetsTables</Role>
      <ShortName>Servicing of Financial Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/ServicingofFinancialAssets</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - Other Earning Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherEarningAssetsTables</Role>
      <ShortName>Other Earning Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherEarningAssets</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - Premises and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/PremisesandEquipmentTables</Role>
      <ShortName>Premises and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/PremisesandEquipment</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/IntangibleAssets</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/Deposits</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - Borrowed Funds (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BorrowedFundsTables</Role>
      <ShortName>Borrowed Funds (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/BorrowedFunds</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - Regulatory Capital Requirements and Regulations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/RegulatoryCapitalRequirementsandRegulationsTables</Role>
      <ShortName>Regulatory Capital Requirements and Regulations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictions</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesNotes</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossTables</Role>
      <ShortName>Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLoss</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - Earnings Per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EarningsPerCommonShareTables</Role>
      <ShortName>Earnings Per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/EarningsPerCommonShare</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - Share-Based Payments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareBasedPaymentsTables</Role>
      <ShortName>Share-Based Payments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareBasedPayments</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - Employee Benefit Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansTables</Role>
      <ShortName>Employee Benefit Plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlans</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - Other Non-Interest Income and Expense (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherNonInterestIncomeandExpenseTables</Role>
      <ShortName>Other Non-Interest Income and Expense (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherNonInterestIncomeandExpense</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxes</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - Derivative Financial Instruments and Hedging Activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsandHedgingActivitiesTables</Role>
      <ShortName>Derivative Financial Instruments and Hedging Activities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/DerivativeFinancialInstrumentsandHedgingActivities</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/FairValueMeasurements</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - Business Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BusinessSegmentInformationTables</Role>
      <ShortName>Business Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/BusinessSegmentInformation</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - Commitments, Contingencies and Guarantees (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CommitmentsContingenciesandGuaranteesTables</Role>
      <ShortName>Commitments, Contingencies and Guarantees (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/CommitmentsContingenciesandGuarantees</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - Parent Company Only Financial Statements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ParentCompanyOnlyFinancialStatementsTables</Role>
      <ShortName>Parent Company Only Financial Statements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.regions.com/role/ParentCompanyOnlyFinancialStatements</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - Summary of Significant Accounting Policies (Supplemental Cash Flows) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesSupplementalCashFlowsDetails</Role>
      <ShortName>Summary of Significant Accounting Policies (Supplemental Cash Flows) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - Summary of Significant Accounting Policies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails</Role>
      <ShortName>Summary of Significant Accounting Policies (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/SummaryofSignificantAccountingPoliciesTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - Variable Interest Entities Affordable Housing Tax Credit Investments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/VariableInterestEntitiesAffordableHousingTaxCreditInvestmentsDetails</Role>
      <ShortName>Variable Interest Entities Affordable Housing Tax Credit Investments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - Debt Securities (Schedule Of Amortized Cost, Gross Unrealized Gains And Losses, And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesScheduleOfAmortizedCostGrossUnrealizedGainsAndLossesAndEstimatedFairValueOfSecuritiesAvailableForSaleAndSecuritiesHeldToMaturityDetails</Role>
      <ShortName>Debt Securities (Schedule Of Amortized Cost, Gross Unrealized Gains And Losses, And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecuritiesTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9955540 - Disclosure - Debt Securities (Schedule Of Cost And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity By Contractual Maturity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesScheduleOfCostAndEstimatedFairValueOfSecuritiesAvailableForSaleAndSecuritiesHeldToMaturityByContractualMaturityDetails</Role>
      <ShortName>Debt Securities (Schedule Of Cost And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity By Contractual Maturity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecuritiesTables</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9955541 - Disclosure - Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesScheduleOfGrossUnrealizedLossesAndEstimatedFairValueOfSecuritiesAvailableForSaleDetails</Role>
      <ShortName>Debt Securities (Schedule Of Gross Unrealized Losses And Estimated Fair Value Of Securities Available For Sale) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecuritiesTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>9955542 - Disclosure - Debt Securities (Schedule of Realized Gain (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesScheduleofRealizedGainLossDetails</Role>
      <ShortName>Debt Securities (Schedule of Realized Gain (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecuritiesTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>9955543 - Disclosure - Debt Securities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DebtSecuritiesNarrativeDetails</Role>
      <ShortName>Debt Securities (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DebtSecuritiesTables</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>9955544 - Disclosure - Loans (Schedule Of Loan Portfolio, Net Of Unearned Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansScheduleOfLoanPortfolioNetOfUnearnedIncomeDetails</Role>
      <ShortName>Loans (Schedule Of Loan Portfolio, Net Of Unearned Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansTables</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>9955545 - Disclosure - Loans And The Allowance For Credit Losses (Analysis Of The Allowance For Credit Losses By Portfolio Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesAnalysisOfTheAllowanceForCreditLossesByPortfolioSegmentDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Analysis Of The Allowance For Credit Losses By Portfolio Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>9955546 - Disclosure - Loans And The Allowance For Credit Losses (Financing Receivables Credit Quality Indicators) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesFinancingReceivablesCreditQualityIndicatorsDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Financing Receivables Credit Quality Indicators) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>9955547 - Disclosure - Loans And The Allowance For Credit Losses (Past Due Financing Receivables) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesPastDueFinancingReceivablesDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Past Due Financing Receivables) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>9955548 - Disclosure - Loans And The Allowance For Credit Losses (Modifications By Class And Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesModificationsByClassAndSegmentDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Modifications By Class And Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>9955549 - Disclosure - Loans And The Allowance For Credit Losses (Financial Impact Of Modifications To Troubled Borrowers) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesFinancialImpactOfModificationsToTroubledBorrowersDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Financial Impact Of Modifications To Troubled Borrowers) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>9955550 - Disclosure - Loans And The Allowance For Credit Losses(Aging and Non-Accrual Performance for Modifications to Troubled Borrowers (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesAgingandNonAccrualPerformanceforModificationstoTroubledBorrowersDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses(Aging and Non-Accrual Performance for Modifications to Troubled Borrowers (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>9955551 - Disclosure - Loans And The Allowance For Credit Losses (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesNarrativeDetails</Role>
      <ShortName>Loans And The Allowance For Credit Losses (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LoansAndTheAllowanceForCreditLossesTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>9955552 - Disclosure - Servicing of Financial Assets (Analysis Of Residential and Commerical MSRs Under The Fair Value Measurement Method) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssetsAnalysisOfResidentialandCommericalMSRsUnderTheFairValueMeasurementMethodDetails</Role>
      <ShortName>Servicing of Financial Assets (Analysis Of Residential and Commerical MSRs Under The Fair Value Measurement Method) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ServicingofFinancialAssetsTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>9955553 - Disclosure - Servicing of Financial Assets (Data And Assumptions Used In The Fair Value Calculation As Well As The Valuation's Sensitivity To Rate Fluctuations Related To Residential and Commercial Mortgage Servicing Rights) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssetsDataAndAssumptionsUsedInTheFairValueCalculationAsWellAsTheValuationsSensitivityToRateFluctuationsRelatedToResidentialandCommercialMortgageServicingRightsDetails</Role>
      <ShortName>Servicing of Financial Assets (Data And Assumptions Used In The Fair Value Calculation As Well As The Valuation's Sensitivity To Rate Fluctuations Related To Residential and Commercial Mortgage Servicing Rights) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ServicingofFinancialAssetsTables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>9955554 - Disclosure - Servicing of Financial Assets (Analysis of Commercial DUS Mortgage Banking Servicing Rights Under Amortized Cost) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssetsAnalysisofCommercialDUSMortgageBankingServicingRightsUnderAmortizedCostDetails</Role>
      <ShortName>Servicing of Financial Assets (Analysis of Commercial DUS Mortgage Banking Servicing Rights Under Amortized Cost) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ServicingofFinancialAssetsTables</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>9955555 - Disclosure - Servicing of Financial Assets (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ServicingofFinancialAssetsNarrativeDetails</Role>
      <ShortName>Servicing of Financial Assets (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ServicingofFinancialAssetsTables</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>9955556 - Disclosure - Other Earning Assets (Schedule Of Investments in Federal Reserve Bank Stock And Federal Home Loan Bank Stock) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherEarningAssetsScheduleOfInvestmentsinFederalReserveBankStockAndFederalHomeLoanBankStockDetails</Role>
      <ShortName>Other Earning Assets (Schedule Of Investments in Federal Reserve Bank Stock And Federal Home Loan Bank Stock) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherEarningAssetsTables</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>9955557 - Disclosure - Other Earning Assets (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherEarningAssetsNarrativeDetails</Role>
      <ShortName>Other Earning Assets (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherEarningAssetsTables</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>9955558 - Disclosure - Premises and Equipment (Schedule of Premises and Equipment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/PremisesandEquipmentScheduleofPremisesandEquipmentDetails</Role>
      <ShortName>Premises and Equipment (Schedule of Premises and Equipment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/PremisesandEquipmentTables</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>9955559 - Disclosure - Intangible Assets (Schedule Of Goodwill By Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IntangibleAssetsScheduleOfGoodwillBySegmentDetails</Role>
      <ShortName>Intangible Assets (Schedule Of Goodwill By Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IntangibleAssetsTables</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>9955560 - Disclosure - Intangible Assets (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IntangibleAssetsNarrativeDetails</Role>
      <ShortName>Intangible Assets (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IntangibleAssetsTables</ParentRole>
      <Position>86</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>9955561 - Disclosure - Deposits (Schedule of Interest-Bearing Deposits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DepositsScheduleofInterestBearingDepositsDetails</Role>
      <ShortName>Deposits (Schedule of Interest-Bearing Deposits) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DepositsTables</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>9955562 - Disclosure - Deposits (Schedule of Aggregate Amount of Maturities of All Time Deposits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DepositsScheduleofAggregateAmountofMaturitiesofAllTimeDepositsDetails</Role>
      <ShortName>Deposits (Schedule of Aggregate Amount of Maturities of All Time Deposits) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/DepositsTables</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>9955563 - Disclosure - Borrowed Funds (Schedule of Long-Term Borrowings) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BorrowedFundsScheduleofLongTermBorrowingsDetails</Role>
      <ShortName>Borrowed Funds (Schedule of Long-Term Borrowings) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/BorrowedFundsTables</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>9955564 - Disclosure - Borrowed Funds (Schedule of Maturities of Long-Term Borrowings) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BorrowedFundsScheduleofMaturitiesofLongTermBorrowingsDetails</Role>
      <ShortName>Borrowed Funds (Schedule of Maturities of Long-Term Borrowings) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/BorrowedFundsTables</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>9955565 - Disclosure - Borrowed Funds (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BorrowedFundsNarrativeDetails</Role>
      <ShortName>Borrowed Funds (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/BorrowedFundsTables</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>9955566 - Disclosure - Regulatory Capital Requirements and Restrictions (Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictionsScheduleofCompliancewithRegulatoryCapitalRequirementsunderBankingRegulationsDetails</Role>
      <ShortName>Regulatory Capital Requirements and Restrictions (Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictions</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>9955567 - Disclosure - Regulatory Capital Requirements and Restrictions Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictionsNarrativeDetails</Role>
      <ShortName>Regulatory Capital Requirements and Restrictions Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/RegulatoryCapitalRequirementsandRestrictions</ParentRole>
      <Position>93</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>9955568 - Disclosure - Leases (Lessee: Information related to Operating Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesLesseeInformationrelatedtoOperatingLeasesDetails</Role>
      <ShortName>Leases (Lessee: Information related to Operating Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesTables</ParentRole>
      <Position>94</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>9955569 - Disclosure - Leases (Lessee: Schedule of Future, Undiscounted Minimum Lease Payments on Operating Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesLesseeScheduleofFutureUndiscountedMinimumLeasePaymentsonOperatingLeasesDetails</Role>
      <ShortName>Leases (Lessee: Schedule of Future, Undiscounted Minimum Lease Payments on Operating Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesTables</ParentRole>
      <Position>95</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>9955570 - Disclosure - Leases (Lessor: Summary of Sales-Type, Direct Financing, Operating and Leveraged Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesLessorSummaryofSalesTypeDirectFinancingOperatingandLeveragedLeasesDetails</Role>
      <ShortName>Leases (Lessor: Summary of Sales-Type, Direct Financing, Operating and Leveraged Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesTables</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>9955571 - Disclosure - Leases (Lessor: Schedule of Minimum Future Payments Due From Customers for Sales-Type, Direct Financing, and Operating Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesLessorScheduleofMinimumFuturePaymentsDueFromCustomersforSalesTypeDirectFinancingandOperatingLeasesDetails</Role>
      <ShortName>Leases (Lessor: Schedule of Minimum Future Payments Due From Customers for Sales-Type, Direct Financing, and Operating Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesTables</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>9955572 - Disclosure - Leases (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/LeasesTables</ParentRole>
      <Position>98</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>9955573 - Disclosure - Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Preferred Stock Issuances) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossPreferredStockIssuancesDetails</Role>
      <ShortName>Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Preferred Stock Issuances) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>9955574 - Disclosure - Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossScheduleofAccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Schedule of Accumulated Other Comprehensive Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>100</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>9955575 - Disclosure - Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossNarrativeDetails</Role>
      <ShortName>Shareholders' Equity and Accumulated Other Comprehensive Income (Loss) (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareholdersEquityandAccumulatedOtherComprehensiveIncomeLossTables</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>9955576 - Disclosure - Earnings Per Common Share (Computation Of Basic And Diluted Earnings (Loss) Per Common Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EarningsPerCommonShareComputationOfBasicAndDilutedEarningsLossPerCommonShareDetails</Role>
      <ShortName>Earnings Per Common Share (Computation Of Basic And Diluted Earnings (Loss) Per Common Share) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EarningsPerCommonShareTables</ParentRole>
      <Position>102</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>9955577 - Disclosure - Share-Based Payments (Summary Of Compensation Costs Recognized In The Consolidated Statements of Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareBasedPaymentsSummaryOfCompensationCostsRecognizedInTheConsolidatedStatementsofOperationsDetails</Role>
      <ShortName>Share-Based Payments (Summary Of Compensation Costs Recognized In The Consolidated Statements of Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareBasedPaymentsTables</ParentRole>
      <Position>103</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>9955578 - Disclosure - Share-Based Payments (Summary Of Restricted Stock Awards And Performance Stock Awards Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareBasedPaymentsSummaryOfRestrictedStockAwardsAndPerformanceStockAwardsActivityDetails</Role>
      <ShortName>Share-Based Payments (Summary Of Restricted Stock Awards And Performance Stock Awards Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareBasedPaymentsTables</ParentRole>
      <Position>104</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>9955579 - Disclosure - Share-Based Payments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/ShareBasedPaymentsNarrativeDetails</Role>
      <ShortName>Share-Based Payments (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/ShareBasedPaymentsTables</ParentRole>
      <Position>105</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>9955580 - Disclosure - Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansScheduleofDefinedBenefitPlansDisclosuresDetails</Role>
      <ShortName>Employee Benefit Plans (Schedule of Defined Benefit Plans Disclosures) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>106</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>9955581 - Disclosure - Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansComponentsOfNetPeriodicPensionCostsDetails</Role>
      <ShortName>Employee Benefit Plans (Components Of Net Periodic Pension Costs) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>107</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>9955582 - Disclosure - Employee Benefit Plans (Schedule of Assumptions Used) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansScheduleofAssumptionsUsedDetails</Role>
      <ShortName>Employee Benefit Plans (Schedule of Assumptions Used) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>108</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>9955583 - Disclosure - Employee Benefit Plans (Presentation Of The Fair Value Of Regions' Qualified Defined-Benefit Pension Plans' Financial Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansPresentationOfTheFairValueOfRegionsQualifiedDefinedBenefitPensionPlansFinancialAssetsDetails</Role>
      <ShortName>Employee Benefit Plans (Presentation Of The Fair Value Of Regions' Qualified Defined-Benefit Pension Plans' Financial Assets) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>109</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>9955584 - Disclosure - Employee Benefit Plans (Information About The Expected Cash Flows For The Qualified and Non-Qualified Pension Plans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansInformationAboutTheExpectedCashFlowsForTheQualifiedandNonQualifiedPensionPlansDetails</Role>
      <ShortName>Employee Benefit Plans (Information About The Expected Cash Flows For The Qualified and Non-Qualified Pension Plans) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>110</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>9955585 - Disclosure - Employee Benefit Plans (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/EmployeeBenefitPlansNarrativeDetails</Role>
      <ShortName>Employee Benefit Plans (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/EmployeeBenefitPlansTables</ParentRole>
      <Position>111</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>9955586 - Disclosure - Other Non-Interest Income and Expense (Other Non-Interest Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherNonInterestIncomeandExpenseOtherNonInterestIncomeDetails</Role>
      <ShortName>Other Non-Interest Income and Expense (Other Non-Interest Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherNonInterestIncomeandExpenseTables</ParentRole>
      <Position>112</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>9955587 - Disclosure - Other Non-Interest Income and Expense (Other Non-Interest Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/OtherNonInterestIncomeandExpenseOtherNonInterestExpenseDetails</Role>
      <ShortName>Other Non-Interest Income and Expense (Other Non-Interest Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/OtherNonInterestIncomeandExpenseTables</ParentRole>
      <Position>113</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>9955588 - Disclosure - Income Taxes (Components Of Income Tax (Benefit) Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesComponentsOfIncomeTaxBenefitExpenseDetails</Role>
      <ShortName>Income Taxes (Components Of Income Tax (Benefit) Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxesTables</ParentRole>
      <Position>114</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>9955589 - Disclosure - Income Taxes (Income Tax Rate Reconciliation) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesIncomeTaxRateReconciliationDetails</Role>
      <ShortName>Income Taxes (Income Tax Rate Reconciliation) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxesTables</ParentRole>
      <Position>115</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>9955590 - Disclosure - Income Taxes (Summary Of Significant Components Of Deferred Tax Assets And Liabilities) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesSummaryOfSignificantComponentsOfDeferredTaxAssetsAndLiabilitiesDetails</Role>
      <ShortName>Income Taxes (Summary Of Significant Components Of Deferred Tax Assets And Liabilities) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxesTables</ParentRole>
      <Position>116</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>9955591 - Disclosure - Income Taxes (Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesReconciliationOfBeginningAndEndingAmountOfUnrecognizedTaxBenefitsDetails</Role>
      <ShortName>Income Taxes (Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxesTables</ParentRole>
      <Position>117</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>9955592 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/IncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/IncomeTaxesTables</ParentRole>
      <Position>118</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>9955593 - Disclosure - Derivative Financial Instruments And Hedging Activities (Schedule Of Derivative Instruments Notional And Fair Values) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesScheduleOfDerivativeInstrumentsNotionalAndFairValuesDetails</Role>
      <ShortName>Derivative Financial Instruments And Hedging Activities (Schedule Of Derivative Instruments Notional And Fair Values) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>9955594 - Disclosure - Derivative Financial Instruments And Hedging Activities (Schedule Of The Effect Of Derivative Instruments On The Statements Of Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesScheduleOfTheEffectOfDerivativeInstrumentsOnTheStatementsOfOperationsDetails</Role>
      <ShortName>Derivative Financial Instruments And Hedging Activities (Schedule Of The Effect Of Derivative Instruments On The Statements Of Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>9955595 - Disclosure - Derivative Financial Instruments and Hedging Activities Derivative Financial Instruments and Hedging Activities (Schedule of Fair Value Hedging Basis Adjustments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsandHedgingActivitiesDerivativeFinancialInstrumentsandHedgingActivitiesScheduleofFairValueHedgingBasisAdjustmentsDetails</Role>
      <ShortName>Derivative Financial Instruments and Hedging Activities Derivative Financial Instruments and Hedging Activities (Schedule of Fair Value Hedging Basis Adjustments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>9955596 - Disclosure - Derivative Financial Instruments And Hedging Activities (Schedule Of Gains (Losses) Recognized Related To Derivatives Not Designated As Hedging Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesScheduleOfGainsLossesRecognizedRelatedToDerivativesNotDesignatedAsHedgingInstrumentsDetails</Role>
      <ShortName>Derivative Financial Instruments And Hedging Activities (Schedule Of Gains (Losses) Recognized Related To Derivatives Not Designated As Hedging Instruments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>9955597 - Disclosure - Derivative Financial Instruments And Hedging Activities (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/DerivativeFinancialInstrumentsAndHedgingActivitiesNarrativeDetails</Role>
      <ShortName>Derivative Financial Instruments And Hedging Activities (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>9955598 - Disclosure - Fair Value Measurements (Schedule Of Assets And Liabilities At Fair Value Measured On A Recurring Basis) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurementsScheduleOfAssetsAndLiabilitiesAtFairValueMeasuredOnARecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements (Schedule Of Assets And Liabilities At Fair Value Measured On A Recurring Basis) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>124</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>9955599 - Disclosure - Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurementsSummaryOfQuantitativeInformationAboutLevel3FairValueMeasurementsDetails</Role>
      <ShortName>Fair Value Measurements (Summary Of Quantitative Information About Level 3 Fair Value Measurements) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>125</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>9955600 - Disclosure - Fair Value Measurements (Fair Value Option, Fair Value and Unpaid Principal Balance) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurementsFairValueOptionFairValueandUnpaidPrincipalBalanceDetails</Role>
      <ShortName>Fair Value Measurements (Fair Value Option, Fair Value and Unpaid Principal Balance) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>126</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>9955601 - Disclosure - Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/FairValueMeasurementsScheduleOfCarryingAmountsAndEstimatedFairValuesOfFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Financial Instruments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>127</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>9955602 - Disclosure - Business Segment Information (Schedule Of Financial Information By Reportable Segment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/BusinessSegmentInformationScheduleOfFinancialInformationByReportableSegmentDetails</Role>
      <ShortName>Business Segment Information (Schedule Of Financial Information By Reportable Segment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/BusinessSegmentInformationTables</ParentRole>
      <Position>128</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>9955603 - Disclosure - Commitments, Contingencies and Guarantees (Credit Risk Of Financial Instruments By Contractual Amounts) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CommitmentsContingenciesandGuaranteesCreditRiskOfFinancialInstrumentsByContractualAmountsDetails</Role>
      <ShortName>Commitments, Contingencies and Guarantees (Credit Risk Of Financial Instruments By Contractual Amounts) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/CommitmentsContingenciesandGuaranteesTables</ParentRole>
      <Position>129</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>9955604 - Disclosure - Commitments, Contingencies and Guarantees (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CommitmentsContingenciesandGuaranteesNarrativeDetails</Role>
      <ShortName>Commitments, Contingencies and Guarantees (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.regions.com/role/CommitmentsContingenciesandGuaranteesTables</ParentRole>
      <Position>130</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>9955605 - Disclosure - Condensed Financial Information Parent Company Balance Sheets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CondensedFinancialInformationParentCompanyBalanceSheetsDetails</Role>
      <ShortName>Condensed Financial Information Parent Company Balance Sheets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>9955606 - Disclosure - Condensed Financial Information Parent Company Statement of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CondensedFinancialInformationParentCompanyStatementofOperationsDetails</Role>
      <ShortName>Condensed Financial Information Parent Company Statement of Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="rf-20251231.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>9955607 - Disclosure - Condensed Financial Information Parent Company Statements of Cash Flow (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.regions.com/role/CondensedFinancialInformationParentCompanyStatementsofCashFlowDetails</Role>
      <ShortName>Condensed Financial Information Parent Company Statements of Cash Flow (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</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-K" isDefinitelyFs="true" isUsgaap="true" original="rf-20251231.htm">rf-20251231.htm</File>
    <File>rf-20251231.xsd</File>
    <File>rf-20251231_cal.xml</File>
    <File>rf-20251231_def.xml</File>
    <File>rf-20251231_lab.xml</File>
    <File>rf-20251231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>rf-20251231_g1.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="5">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="4420">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="15">http://xbrl.sec.gov/cyd/2025</BaseTaxonomy>
    <BaseTaxonomy items="47">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="5">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
