<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>2186</ContextCount>
  <ElementCount>811</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>527</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>1001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1002 - Statement - CONSOLIDATED STATEMENTS OF FINANCIAL POSITION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ConsolidatedStatementsOfFinancialPosition</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF FINANCIAL POSITION</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1003 - Statement - CONSOLIDATED STATEMENT OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ConsolidatedStatementOfIncome</Role>
      <ShortName>CONSOLIDATED STATEMENT OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1004 - Statement - CONSOLIDATED STATEMENT OF OTHER COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ConsolidatedStatementOfOtherComprehensiveIncome</Role>
      <ShortName>CONSOLIDATED STATEMENT OF OTHER COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1005 - Statement - CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ConsolidatedStatementOfChangesInShareholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1006 - Statement - CONSOLIDATED STATEMENT OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ConsolidatedStatementOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENT OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1007 - Disclosure - Accounting Policies and Basis for Preparation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparation</Role>
      <ShortName>Accounting Policies and Basis for Preparation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1008 - Disclosure - Critical Accounting Policies and Estimates</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CriticalAccountingPoliciesAndEstimates</Role>
      <ShortName>Critical Accounting Policies and Estimates</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>1009 - Disclosure - Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialInstruments</Role>
      <ShortName>Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>1010 - Disclosure - Fair Values</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FairValues</Role>
      <ShortName>Fair Values</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>1011 - Disclosure - Cash and Cash Equivalents</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CashAndCashEquivalents</Role>
      <ShortName>Cash and Cash Equivalents</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>1012 - Disclosure - Debt Securities at Fair Value through Profit or Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesAtFairValueThroughProfitOrLoss</Role>
      <ShortName>Debt Securities at Fair Value through Profit or Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>1013 - Disclosure - Derivative Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DerivativeFinancialInstruments</Role>
      <ShortName>Derivative Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>1014 - Disclosure - Repurchase Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RepurchaseTransactions</Role>
      <ShortName>Repurchase Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>1015 - Disclosure - Other Financial Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialAssets</Role>
      <ShortName>Other Financial Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>1016 - Disclosure - Loans and Other Financing</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansAndOtherFinancing</Role>
      <ShortName>Loans and Other Financing</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>1017 - Disclosure - Other Debt Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherDebtSecurities</Role>
      <ShortName>Other Debt Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>1018 - Disclosure - Financial Assets Pledged as Collateral</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialAssetsPledgedAsCollateral</Role>
      <ShortName>Financial Assets Pledged as Collateral</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>1019 - Disclosure - Current Income Tax Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CurrentIncomeTaxAssets</Role>
      <ShortName>Current Income Tax Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>1020 - Disclosure - Investments In Equity Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/InvestmentsInEquityInstruments</Role>
      <ShortName>Investments In Equity Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>1021 - Disclosure - Equity Investments in Subsidiaries, Associates and Joint Ventures</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EquityInvestmentsInSubsidiariesAssociatesAndJointVentures</Role>
      <ShortName>Equity Investments in Subsidiaries, Associates and Joint Ventures</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>1022 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>1023 - Disclosure - Property, Plant and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/PropertyPlantAndEquipment</Role>
      <ShortName>Property, Plant and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>1024 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>1025 - Disclosure - Deferred Income Tax Assets/Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DeferredIncomeTaxAssetsLiabilities</Role>
      <ShortName>Deferred Income Tax Assets/Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>1026 - Disclosure - Assets/Liabilities for Insurance Contracts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContracts</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>1027 - Disclosure - Other Non-financial Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialAssets</Role>
      <ShortName>Other Non-financial Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>1028 - Disclosure - Non-current Assets Held for Sale and Discontinued Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonCurrentAssetsHeldForSaleAndDiscontinuedOperations</Role>
      <ShortName>Non-current Assets Held for Sale and Discontinued Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>1029 - Disclosure - Deposits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/Deposits</Role>
      <ShortName>Deposits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>1030 - Disclosure - Liablilities Measured at Fair Value Through Profit or Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LiablilitiesMeasuredAtFairValueThroughProfitOrLoss</Role>
      <ShortName>Liablilities Measured at Fair Value Through Profit or Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>1031 - Disclosure - Other Financial Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialLiabilities</Role>
      <ShortName>Other Financial Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>1032 - Disclosure - Loans from the Argentine Central Bank and Other Financial Institutions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansFromTheArgentineCentralBankAndOtherFinancialInstitutions</Role>
      <ShortName>Loans from the Argentine Central Bank and Other Financial Institutions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>1033 - Disclosure - Debt Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecurities</Role>
      <ShortName>Debt Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>1034 - Disclosure - Subordinated Debt Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SubordinatedDebtSecurities</Role>
      <ShortName>Subordinated Debt Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>1035 - Disclosure - Provisions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/Provisions</Role>
      <ShortName>Provisions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>1036 - Disclosure - Other Non-financial Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialLiabilities</Role>
      <ShortName>Other Non-financial Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>1037 - Disclosure - Capital Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalStock</Role>
      <ShortName>Capital Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>1038 - Disclosure - Income Statement Breakdown</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeStatementBreakdown</Role>
      <ShortName>Income Statement Breakdown</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>1039 - Disclosure - Exchange Rate Differences on Gold and Foreign Currency</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ExchangeRateDifferencesOnGoldAndForeignCurrency</Role>
      <ShortName>Exchange Rate Differences on Gold and Foreign Currency</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>1040 - Disclosure - Other Operating Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingIncome</Role>
      <ShortName>Other Operating Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>1041 - Disclosure - Underwriting Income from Insurance Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/UnderwritingIncomeFromInsuranceBusiness</Role>
      <ShortName>Underwriting Income from Insurance Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>1042 - Disclosure - Loan Loss Provision</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoanLossProvision</Role>
      <ShortName>Loan Loss Provision</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>1043 - Disclosure - Personnel Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/PersonnelExpenses</Role>
      <ShortName>Personnel Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>1044 - Disclosure - Administrative Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdministrativeExpenses</Role>
      <ShortName>Administrative Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>1045 - Disclosure - Depreciation and Impairment of Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DepreciationAndImpairmentOfAssets</Role>
      <ShortName>Depreciation and Impairment of Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>1046 - Disclosure - Other Operating Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingExpenses</Role>
      <ShortName>Other Operating Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>1047 - Disclosure - Income Tax/Deferred Tax</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeTaxDeferredTax</Role>
      <ShortName>Income Tax/Deferred Tax</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>1048 - Disclosure - Dividends</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/Dividends</Role>
      <ShortName>Dividends</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>1049 - Disclosure - Earnings Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EarningsPerShare</Role>
      <ShortName>Earnings Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>1050 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>1051 - Disclosure - Capital Management and Risk Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPolicies</Role>
      <ShortName>Capital Management and Risk Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>1052 - Disclosure - Contingencies and Commitments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ContingenciesAndCommitments</Role>
      <ShortName>Contingencies and Commitments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>1053 - Disclosure - Offsetting of Financial Assets and Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffsettingOfFinancialAssetsAndLiabilities</Role>
      <ShortName>Offsetting of Financial Assets and Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>1054 - Disclosure - Off-balance Sheet Items</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItems</Role>
      <ShortName>Off-balance Sheet Items</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>1055 - Disclosure - Transfer of Financial Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/TransferOfFinancialAssets</Role>
      <ShortName>Transfer of Financial Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>1056 - Disclosure - Non-controlling Interest</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonControllingInterest</Role>
      <ShortName>Non-controlling Interest</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>1057 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>1058 - Disclosure - Acquisition of Debt Securities Under Section 35 BIS of Financial Institutions Law</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AcquisitionOfDebtSecuritiesUnderSection35BisOfFinancialInstitutionsLaw</Role>
      <ShortName>Acquisition of Debt Securities Under Section 35 BIS of Financial Institutions Law</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>1059 - Disclosure - Additional Information Required by the Argentine Central Bank</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBank</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>1060 - Disclosure - Economic Context Where the Group Operates</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EconomicContextWhereTheGroupOperates</Role>
      <ShortName>Economic Context Where the Group Operates</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>1061 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>1062 - Disclosure - Accounting Policies and Basis for Preparation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparationPolicies</Role>
      <ShortName>Accounting Policies and Basis for Preparation (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparation</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>1063 - Disclosure - Accounting Policies and Basis for Preparation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparationTables</Role>
      <ShortName>Accounting Policies and Basis for Preparation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparation</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>1064 - Disclosure - Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialInstrumentsTables</Role>
      <ShortName>Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/FinancialInstruments</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>1065 - Disclosure - Fair Values (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FairValuesTables</Role>
      <ShortName>Fair Values (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/FairValues</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>1066 - Disclosure - Cash and Cash Equivalents (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CashAndCashEquivalentsTables</Role>
      <ShortName>Cash and Cash Equivalents (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/CashAndCashEquivalents</ParentRole>
      <Position>66</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>1067 - Disclosure - Derivative Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DerivativeFinancialInstrumentsTables</Role>
      <ShortName>Derivative Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/DerivativeFinancialInstruments</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>1068 - Disclosure - Repurchase Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RepurchaseTransactionsTables</Role>
      <ShortName>Repurchase Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/RepurchaseTransactions</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>1069 - Disclosure - Other Financial Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialAssetsTables</Role>
      <ShortName>Other Financial Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherFinancialAssets</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>1070 - Disclosure - Loans and Other Financing (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansAndOtherFinancingTables</Role>
      <ShortName>Loans and Other Financing (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/LoansAndOtherFinancing</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>1071 - Disclosure - Financial Assets Pledged as Collateral (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialAssetsPledgedAsCollateralTables</Role>
      <ShortName>Financial Assets Pledged as Collateral (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/FinancialAssetsPledgedAsCollateral</ParentRole>
      <Position>71</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>1072 - Disclosure - Current Income Tax Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CurrentIncomeTaxAssetsTables</Role>
      <ShortName>Current Income Tax Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/CurrentIncomeTaxAssets</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>1073 - Disclosure - Equity Investments in Subsidiaries, Associates and Joint Ventures (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EquityInvestmentsInSubsidiariesAssociatesAndJointVenturesTables</Role>
      <ShortName>Equity Investments in Subsidiaries, Associates and Joint Ventures (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/EquityInvestmentsInSubsidiariesAssociatesAndJointVentures</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>1074 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/Leases</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>1075 - Disclosure - Deferred Income Tax Assets/Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DeferredIncomeTaxAssetsLiabilitiesTables</Role>
      <ShortName>Deferred Income Tax Assets/Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/DeferredIncomeTaxAssetsLiabilities</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>1076 - Disclosure - Assets/Liabilities for Insurance Contracts (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsTables</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContracts</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>1077 - Disclosure - Other Non-financial Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialAssetsTables</Role>
      <ShortName>Other Non-financial Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherNonFinancialAssets</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>1078 - Disclosure - Non-current Assets Held for Sale and Discontinued Operations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonCurrentAssetsHeldForSaleAndDiscontinuedOperationsTables</Role>
      <ShortName>Non-current Assets Held for Sale and Discontinued Operations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/NonCurrentAssetsHeldForSaleAndDiscontinuedOperations</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>1079 - Disclosure - Deposits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DepositsTables</Role>
      <ShortName>Deposits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/Deposits</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>1080 - Disclosure - Other Financial Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialLiabilitiesTables</Role>
      <ShortName>Other Financial Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherFinancialLiabilities</ParentRole>
      <Position>80</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>1081 - Disclosure - Loans from the Argentine Central Bank and Other Financial Institutions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansFromTheArgentineCentralBankAndOtherFinancialInstitutionsTables</Role>
      <ShortName>Loans from the Argentine Central Bank and Other Financial Institutions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/LoansFromTheArgentineCentralBankAndOtherFinancialInstitutions</ParentRole>
      <Position>81</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>1082 - Disclosure - Debt Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesTables</Role>
      <ShortName>Debt Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/DebtSecuritiesAtFairValueThroughProfitOrLoss</ParentRole>
      <Position>82</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>1083 - Disclosure - Subordinated Debt Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SubordinatedDebtSecuritiesTables</Role>
      <ShortName>Subordinated Debt Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/SubordinatedDebtSecurities</ParentRole>
      <Position>83</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>1084 - Disclosure - Provisions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ProvisionsTables</Role>
      <ShortName>Provisions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/Provisions</ParentRole>
      <Position>84</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>1085 - Disclosure - Other Non-financial Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialLiabilitiesTables</Role>
      <ShortName>Other Non-financial Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherNonFinancialLiabilities</ParentRole>
      <Position>85</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>1086 - Disclosure - Exchange Rate Differences on Gold and Foreign Currency (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ExchangeRateDifferencesOnGoldAndForeignCurrencyTables</Role>
      <ShortName>Exchange Rate Differences on Gold and Foreign Currency (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/ExchangeRateDifferencesOnGoldAndForeignCurrency</ParentRole>
      <Position>86</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>1087 - Disclosure - Other Operating Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingIncomeTables</Role>
      <ShortName>Other Operating Income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherOperatingIncome</ParentRole>
      <Position>87</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>1088 - Disclosure - Underwriting Income from Insurance Business (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/UnderwritingIncomeFromInsuranceBusinessTables</Role>
      <ShortName>Underwriting Income from Insurance Business (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/UnderwritingIncomeFromInsuranceBusiness</ParentRole>
      <Position>88</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>1089 - Disclosure - Personnel Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/PersonnelExpensesTables</Role>
      <ShortName>Personnel Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/PersonnelExpenses</ParentRole>
      <Position>89</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>1090 - Disclosure - Administrative Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdministrativeExpensesTables</Role>
      <ShortName>Administrative Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/AdministrativeExpenses</ParentRole>
      <Position>90</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>1091 - Disclosure - Depreciation and Impairment of Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DepreciationAndImpairmentOfAssetsTables</Role>
      <ShortName>Depreciation and Impairment of Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/DepreciationAndImpairmentOfAssets</ParentRole>
      <Position>91</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>1092 - Disclosure - Other Operating Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingExpensesTables</Role>
      <ShortName>Other Operating Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OtherOperatingExpenses</ParentRole>
      <Position>92</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>1093 - Disclosure - Income Tax/Deferred Tax (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeTaxDeferredTaxTables</Role>
      <ShortName>Income Tax/Deferred Tax (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/IncomeTaxDeferredTax</ParentRole>
      <Position>93</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>1094 - Disclosure - Earnings Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/EarningsPerShare</ParentRole>
      <Position>94</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>1095 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/SegmentReporting</ParentRole>
      <Position>95</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>1096 - Disclosure - Capital Management and Risk Policies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesTables</Role>
      <ShortName>Capital Management and Risk Policies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/CapitalManagementAndRiskPolicies</ParentRole>
      <Position>96</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>1097 - Disclosure - Contingencies and Commitments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ContingenciesAndCommitmentsTables</Role>
      <ShortName>Contingencies and Commitments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/ContingenciesAndCommitments</ParentRole>
      <Position>97</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>1098 - Disclosure - Offsetting of Financial Assets and Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffsettingOfFinancialAssetsAndLiabilitiesTables</Role>
      <ShortName>Offsetting of Financial Assets and Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OffsettingOfFinancialAssetsAndLiabilities</ParentRole>
      <Position>98</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>1099 - Disclosure - Off-balance Sheet Items (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsTables</Role>
      <ShortName>Off-balance Sheet Items (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/OffBalanceSheetItems</ParentRole>
      <Position>99</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>1100 - Disclosure - Non-controlling Interest (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonControllingInterestTables</Role>
      <ShortName>Non-controlling Interest (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/NonControllingInterest</ParentRole>
      <Position>100</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>1101 - Disclosure - Related Party Transactions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactionsTables</Role>
      <ShortName>Related Party Transactions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/RelatedPartyTransactions</ParentRole>
      <Position>101</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>1102 - Disclosure - Additional Information Required by the Argentine Central Bank (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankTables</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBank</ParentRole>
      <Position>102</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>1103 - Disclosure - Accounting Policies and Basis for Preparation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparationAdditionalInformationDetail</Role>
      <ShortName>Accounting Policies and Basis for Preparation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>1104 - Disclosure - Accounting Policies and Basis for Preparation - Summary of measurement of lease liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparationSummaryOfMeasurementOfLeaseLiabilitiesDetail</Role>
      <ShortName>Accounting Policies and Basis for Preparation - Summary of measurement of lease liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>1105 - Disclosure - Accounting Policies and Basis for Preparation - Summary of Main Commissions Earned by the Bank (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AccountingPoliciesAndBasisForPreparationSummaryOfMainCommissionsEarnedByTheBankDetail</Role>
      <ShortName>Accounting Policies and Basis for Preparation - Summary of Main Commissions Earned by the Bank (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>1106 - Disclosure - Financial Instruments - Schedule of Portfolios of Financial Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialInstrumentsScheduleOfPortfoliosOfFinancialInstrumentsDetail</Role>
      <ShortName>Financial Instruments - Schedule of Portfolios of Financial Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>1107 - Disclosure - Fair Values - Schedule of Financial Instruments Measured at Fair Value (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FairValuesScheduleOfFinancialInstrumentsMeasuredAtFairValueDetail</Role>
      <ShortName>Fair Values - Schedule of Financial Instruments Measured at Fair Value (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>1108 - Disclosure - Fair Values - Summary of Changes in Instruments Included in Fair Value Level 3 (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FairValuesSummaryOfChangesInInstrumentsIncludedInFairValueLevel3Detail</Role>
      <ShortName>Fair Values - Summary of Changes in Instruments Included in Fair Value Level 3 (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>1109 - Disclosure - Fair Values - Summary of Assets and Liabilities Recorded at Amortized Cost (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FairValuesSummaryOfAssetsAndLiabilitiesRecordedAtAmortizedCostDetail</Role>
      <ShortName>Fair Values - Summary of Assets and Liabilities Recorded at Amortized Cost (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>1110 - Disclosure - Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CashAndCashEquivalentsSummaryOfCashAndCashEquivalentsDetail</Role>
      <ShortName>Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>1111 - Disclosure - Derivative Financial Instruments - Summary of Derivative Instrument Transactions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DerivativeFinancialInstrumentsSummaryOfDerivativeInstrumentTransactionsDetail</Role>
      <ShortName>Derivative Financial Instruments - Summary of Derivative Instrument Transactions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>1112 - Disclosure - Repurchase Transactions - Summary of Repo Transactions and Reverse Repurchase Transactions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RepurchaseTransactionsSummaryOfRepoTransactionsAndReverseRepurchaseTransactionsDetail</Role>
      <ShortName>Repurchase Transactions - Summary of Repo Transactions and Reverse Repurchase Transactions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>1113 - Disclosure - Repurchase Transactions - Summary of Repurchase Agreements in Financial Assets Pledged as Collateral and Reverse Repurchase Agreements in Off-Balance Sheet Items (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RepurchaseTransactionsSummaryOfRepurchaseAgreementsInFinancialAssetsPledgedAsCollateralAndReverseRepurchaseAgreementsInOffBalanceSheetItemsDetail</Role>
      <ShortName>Repurchase Transactions - Summary of Repurchase Agreements in Financial Assets Pledged as Collateral and Reverse Repurchase Agreements in Off-Balance Sheet Items (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>1114 - Disclosure - Other Financial Assets - Summary of Other Financial Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialAssetsSummaryOfOtherFinancialAssetsDetail</Role>
      <ShortName>Other Financial Assets - Summary of Other Financial Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>1115 - Disclosure - Other Financial Assets - Summary of Credit Rating Quality Analysis of Other Financial Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialAssetsSummaryOfCreditRatingQualityAnalysisOfOtherFinancialAssetsDetail</Role>
      <ShortName>Other Financial Assets - Summary of Credit Rating Quality Analysis of Other Financial Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>1116 - Disclosure - Loans and Other Financing - Summary of Net Loans and Other Financing (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansAndOtherFinancingSummaryOfNetLoansAndOtherFinancingDetail</Role>
      <ShortName>Loans and Other Financing - Summary of Net Loans and Other Financing (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>1117 - Disclosure - Financial Assets Pledged as Collateral - Summary of Financial Assets Pledged as Collateral (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/FinancialAssetsPledgedAsCollateralSummaryOfFinancialAssetsPledgedAsCollateralDetail</Role>
      <ShortName>Financial Assets Pledged as Collateral - Summary of Financial Assets Pledged as Collateral (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>1118 - Disclosure - Current Income Tax Assets - Summary of Current Income Tax Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CurrentIncomeTaxAssetsSummaryOfCurrentIncomeTaxAssetsDetail</Role>
      <ShortName>Current Income Tax Assets - Summary of Current Income Tax Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>1119 - Disclosure - Equity Investments in Subsidiaries, Associates and Joint Ventures - Summary of Equity Investments in Subsidiaries (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EquityInvestmentsInSubsidiariesAssociatesAndJointVenturesSummaryOfEquityInvestmentsInSubsidiariesDetail</Role>
      <ShortName>Equity Investments in Subsidiaries, Associates and Joint Ventures - Summary of Equity Investments in Subsidiaries (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>1120 - Disclosure - Equity Investments in Subsidiaries, Associates and Joint Ventures - Summary of Balances of Subsidiaries, According to the IFRS-based Accounting Framework (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EquityInvestmentsInSubsidiariesAssociatesAndJointVenturesSummaryOfBalancesOfSubsidiariesAccordingToTheIfrsBasedAccountingFrameworkDetail</Role>
      <ShortName>Equity Investments in Subsidiaries, Associates and Joint Ventures - Summary of Balances of Subsidiaries, According to the IFRS-based Accounting Framework (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>1121 - Disclosure - Leases - Summary of detailed information about lease assets and liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LeasesSummaryOfDetailedInformationAboutLeaseAssetsAndLiabilitiesDetail</Role>
      <ShortName>Leases - Summary of detailed information about lease assets and liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>1122 - Disclosure - Lease - Summary of detailed information about income statement disclosures of leases (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LeaseSummaryOfDetailedInformationAboutIncomeStatementDisclosuresOfLeasesDetail</Role>
      <ShortName>Lease - Summary of detailed information about income statement disclosures of leases (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>1123 - Disclosure - Leases - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LeasesAdditionalInformationDetail</Role>
      <ShortName>Leases - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>1124 - Disclosure - Leases - Summary of quantitative information about right of use assets and lease liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LeasesSummaryOfQuantitativeInformationAboutRightOfUseAssetsAndLeaseLiabilitiesDetail</Role>
      <ShortName>Leases - Summary of quantitative information about right of use assets and lease liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>1125 - Disclosure - Deferred Income Tax Assets/Liabilities - Summary of Changes in Deferred Income Tax Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DeferredIncomeTaxAssetsLiabilitiesSummaryOfChangesInDeferredIncomeTaxAssetsAndLiabilitiesDetail</Role>
      <ShortName>Deferred Income Tax Assets/Liabilities - Summary of Changes in Deferred Income Tax Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>125</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>1126 - Disclosure - Deferred Income Tax Assets/Liabilities - Summary of Expiration Dates of Tax Loss Carry-forwards (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DeferredIncomeTaxAssetsLiabilitiesSummaryOfExpirationDatesOfTaxLossCarryForwardsDetail</Role>
      <ShortName>Deferred Income Tax Assets/Liabilities - Summary of Expiration Dates of Tax Loss Carry-forwards (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>126</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>1127 - Disclosure - Assets/Liabilities for Insurance Contracts - Assets Related to Insurance Contracts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsAssetsRelatedToInsuranceContractsDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Assets Related to Insurance Contracts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>127</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>1128 - Disclosure - Assets/Liabilities for Insurance Contracts - Liabilities Related to Insurance Contracts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsLiabilitiesRelatedToInsuranceContractsDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Liabilities Related to Insurance Contracts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>1129 - Disclosure - Assets/Liabilities for Insurance Contracts - Summary of Debts with Insureds (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsSummaryOfDebtsWithInsuredsDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Summary of Debts with Insureds (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>1130 - Disclosure - Assets/Liabilities for Insurance Contracts - Summary of Net Gross and Reinsurers Share for Amounts Arising from Insurance Contracts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsSummaryOfNetGrossAndReinsurersShareForAmountsArisingFromInsuranceContractsDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Summary of Net Gross and Reinsurers Share for Amounts Arising from Insurance Contracts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>1131 - Disclosure - Assets/Liabilities for Insurance Contracts - Summary of debts with producers (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsSummaryOfDebtsWithProducersDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Summary of debts with producers (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>1132 - Disclosure - Assets/Liabilities for Insurance Contracts - Summary of Statutory Reserves (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsSummaryOfStatutoryReservesDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Summary of Statutory Reserves (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>1133 - Disclosure - Assets/Liabilities for Insurance Contracts - Summary of Assumption Used for Current Estimates of Future Cash Flows Derived from Insurance Contract (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AssetsLiabilitiesForInsuranceContractsSummaryOfAssumptionUsedForCurrentEstimatesOfFutureCashFlowsDerivedFromInsuranceContractDetail</Role>
      <ShortName>Assets/Liabilities for Insurance Contracts - Summary of Assumption Used for Current Estimates of Future Cash Flows Derived from Insurance Contract (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>1134 - Disclosure - Other Non-financial Assets - Summary of Other Non-financial Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialAssetsSummaryOfOtherNonFinancialAssetsDetail</Role>
      <ShortName>Other Non-financial Assets - Summary of Other Non-financial Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>134</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>1135 - Disclosure - Non-current Assets Held for Sale and Discontinued Operations - Summary of Classification of Assets as Assets Held for Sale and Discontinued Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonCurrentAssetsHeldForSaleAndDiscontinuedOperationsSummaryOfClassificationOfAssetsAsAssetsHeldForSaleAndDiscontinuedOperationsDetail</Role>
      <ShortName>Non-current Assets Held for Sale and Discontinued Operations - Summary of Classification of Assets as Assets Held for Sale and Discontinued Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>135</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R136.htm</HtmlFileName>
      <LongName>1136 - Disclosure - Non-current Assets Held for Sale and Discontinued Operations - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonCurrentAssetsHeldForSaleAndDiscontinuedOperationsAdditionalInformationDetail</Role>
      <ShortName>Non-current Assets Held for Sale and Discontinued Operations - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>136</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>1137 - Disclosure - Deposits - Summary of Deposits (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DepositsSummaryOfDepositsDetail</Role>
      <ShortName>Deposits - Summary of Deposits (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>137</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>1138 - Disclosure - Other Financial Liabilities - Summary of Other Financial Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherFinancialLiabilitiesSummaryOfOtherFinancialLiabilitiesDetail</Role>
      <ShortName>Other Financial Liabilities - Summary of Other Financial Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>138</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R139.htm</HtmlFileName>
      <LongName>1139 - Disclosure - Loans from the Argentina Central Bank and Other Financial Institutions - Summary of Loans from the Argentina Central Bank and Other Financial Institutions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansFromTheArgentinaCentralBankAndOtherFinancialInstitutionsSummaryOfLoansFromTheArgentinaCentralBankAndOtherFinancialInstitutionsDetail</Role>
      <ShortName>Loans from the Argentina Central Bank and Other Financial Institutions - Summary of Loans from the Argentina Central Bank and Other Financial Institutions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>139</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R140.htm</HtmlFileName>
      <LongName>1140 - Disclosure - Loans from the Argentina Central Bank and Other Financial Institutions - Schedule of Credit Lines with Local and International Financial Institutions and Entities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/LoansFromTheArgentinaCentralBankAndOtherFinancialInstitutionsScheduleOfCreditLinesWithLocalAndInternationalFinancialInstitutionsAndEntitiesDetail</Role>
      <ShortName>Loans from the Argentina Central Bank and Other Financial Institutions - Schedule of Credit Lines with Local and International Financial Institutions and Entities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>140</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>1141 - Disclosure - Debt Securities - Summary of Breakdown of the Global Programs for the Issuance of Negotiable Obligations Outstanding (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesSummaryOfBreakdownOfTheGlobalProgramsForTheIssuanceOfNegotiableObligationsOutstandingDetail</Role>
      <ShortName>Debt Securities - Summary of Breakdown of the Global Programs for the Issuance of Negotiable Obligations Outstanding (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>141</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>1142 - Disclosure - Debt Securities - Summary of Unsubordinated Debt Securities Outstanding Issued Under the Global Programs (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesSummaryOfUnsubordinatedDebtSecuritiesOutstandingIssuedUnderTheGlobalProgramsDetail</Role>
      <ShortName>Debt Securities - Summary of Unsubordinated Debt Securities Outstanding Issued Under the Global Programs (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>142</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R143.htm</HtmlFileName>
      <LongName>1143 - Disclosure - Debt Securities - Summary of Unsubordinated Debt Securities Outstanding Issued Under the Global Programs (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesSummaryOfUnsubordinatedDebtSecuritiesOutstandingIssuedUnderTheGlobalProgramsParentheticalDetail</Role>
      <ShortName>Debt Securities - Summary of Unsubordinated Debt Securities Outstanding Issued Under the Global Programs (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>143</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R144.htm</HtmlFileName>
      <LongName>1144 - Disclosure - Debt Securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesAdditionalInformationDetail</Role>
      <ShortName>Debt Securities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>144</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R145.htm</HtmlFileName>
      <LongName>1145 - Disclosure - Debt Securities - Summary of Repurchases of Own Debt Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DebtSecuritiesSummaryOfRepurchasesOfOwnDebtSecuritiesDetail</Role>
      <ShortName>Debt Securities - Summary of Repurchases of Own Debt Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>145</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R146.htm</HtmlFileName>
      <LongName>1146 - Disclosure - Subordinated Debt Securities - Summary of Subordinated Negotiable Obligations Not Convertible Into Shares Issued Under Global Programs (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SubordinatedDebtSecuritiesSummaryOfSubordinatedNegotiableObligationsNotConvertibleIntoSharesIssuedUnderGlobalProgramsDetail</Role>
      <ShortName>Subordinated Debt Securities - Summary of Subordinated Negotiable Obligations Not Convertible Into Shares Issued Under Global Programs (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>146</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R147.htm</HtmlFileName>
      <LongName>1147 - Disclosure - Subordinated Debt Securities - Summary of Subordinated Negotiable Obligations Not Convertible Into Shares Issued Under Global Programs (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SubordinatedDebtSecuritiesSummaryOfSubordinatedNegotiableObligationsNotConvertibleIntoSharesIssuedUnderGlobalProgramsParentheticalDetail</Role>
      <ShortName>Subordinated Debt Securities - Summary of Subordinated Negotiable Obligations Not Convertible Into Shares Issued Under Global Programs (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>147</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R148.htm</HtmlFileName>
      <LongName>1148 - Disclosure - Provisions - Summary of Provisions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ProvisionsSummaryOfProvisionsDetail</Role>
      <ShortName>Provisions - Summary of Provisions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>148</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R149.htm</HtmlFileName>
      <LongName>1149 - Disclosure - Other Non-financial Liabilities - Summary of Other Non-financial Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialLiabilitiesSummaryOfOtherNonFinancialLiabilitiesDetail</Role>
      <ShortName>Other Non-financial Liabilities - Summary of Other Non-financial Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>149</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R150.htm</HtmlFileName>
      <LongName>1150 - Disclosure - Other Non-financial Liabilities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialLiabilitiesAdditionalInformationDetail</Role>
      <ShortName>Other Non-financial Liabilities - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>150</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R151.htm</HtmlFileName>
      <LongName>1151 - Disclosure - Other Non-financial Liabilities - Summary of Estimated Use of Liability (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherNonFinancialLiabilitiesSummaryOfEstimatedUseOfLiabilityDetail</Role>
      <ShortName>Other Non-financial Liabilities - Summary of Estimated Use of Liability (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>151</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R152.htm</HtmlFileName>
      <LongName>1152 - Disclosure - Capital Stock - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalStockAdditionalInformationDetail</Role>
      <ShortName>Capital Stock - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>152</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R153.htm</HtmlFileName>
      <LongName>1153 - Disclosure - Exchange Rate Differences on Gold and Foreign Currency - Summary of Gold and Foreign Currency Quotation Differences (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ExchangeRateDifferencesOnGoldAndForeignCurrencySummaryOfGoldAndForeignCurrencyQuotationDifferencesDetail</Role>
      <ShortName>Exchange Rate Differences on Gold and Foreign Currency - Summary of Gold and Foreign Currency Quotation Differences (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>153</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R154.htm</HtmlFileName>
      <LongName>1154 - Disclosure - Other Operating Income - Summary of Other Operating Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingIncomeSummaryOfOtherOperatingIncomeDetail</Role>
      <ShortName>Other Operating Income - Summary of Other Operating Income (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>154</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R155.htm</HtmlFileName>
      <LongName>1155 - Disclosure - Underwriting Income from Insurance Business - Summary of Underwriting Income from Insurance Business (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/UnderwritingIncomeFromInsuranceBusinessSummaryOfUnderwritingIncomeFromInsuranceBusinessDetail</Role>
      <ShortName>Underwriting Income from Insurance Business - Summary of Underwriting Income from Insurance Business (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>155</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R156.htm</HtmlFileName>
      <LongName>1156 - Disclosure - Personnel Expenses - Summary of Personnel Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/PersonnelExpensesSummaryOfPersonnelExpensesDetail</Role>
      <ShortName>Personnel Expenses - Summary of Personnel Expenses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>156</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R157.htm</HtmlFileName>
      <LongName>1157 - Disclosure - Administrative Expenses - Summary of Expenses by Nature and Function (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdministrativeExpensesSummaryOfExpensesByNatureAndFunctionDetail</Role>
      <ShortName>Administrative Expenses - Summary of Expenses by Nature and Function (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>157</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R158.htm</HtmlFileName>
      <LongName>1158 - Disclosure - Depreciation and Impairment of Assets - Summary of Depreciation and Impairment of Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DepreciationAndImpairmentOfAssetsSummaryOfDepreciationAndImpairmentOfAssetsDetail</Role>
      <ShortName>Depreciation and Impairment of Assets - Summary of Depreciation and Impairment of Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>158</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R159.htm</HtmlFileName>
      <LongName>1159 - Disclosure - Other Operating Expenses - Summary of Other Operating Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OtherOperatingExpensesSummaryOfOtherOperatingExpensesDetail</Role>
      <ShortName>Other Operating Expenses - Summary of Other Operating Expenses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>159</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R160.htm</HtmlFileName>
      <LongName>1160 - Disclosure - Income Tax/Deferred Tax - Summary of Reconciliation of Income Tax Charged to Income (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeTaxDeferredTaxSummaryOfReconciliationOfIncomeTaxChargedToIncomeDetail</Role>
      <ShortName>Income Tax/Deferred Tax - Summary of Reconciliation of Income Tax Charged to Income (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>160</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R161.htm</HtmlFileName>
      <LongName>1161 - Disclosure - Income Tax/Deferred Tax - Summary of Current Income Tax Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeTaxDeferredTaxSummaryOfCurrentIncomeTaxLiabilitiesDetail</Role>
      <ShortName>Income Tax/Deferred Tax - Summary of Current Income Tax Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>161</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R162.htm</HtmlFileName>
      <LongName>1162 - Disclosure - Income Tax/Deferred Tax - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/IncomeTaxDeferredTaxAdditionalInformationDetail</Role>
      <ShortName>Income Tax/Deferred Tax - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>162</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R163.htm</HtmlFileName>
      <LongName>1163 - Disclosure - Dividends - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/DividendsAdditionalInformationDetail</Role>
      <ShortName>Dividends - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>163</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R164.htm</HtmlFileName>
      <LongName>1164 - Disclosure - Earnings Per Share - Schedule of Earnings Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/EarningsPerShareScheduleOfEarningsPerShareDetail</Role>
      <ShortName>Earnings Per Share - Schedule of Earnings Per Share (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>164</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R165.htm</HtmlFileName>
      <LongName>1165 - Disclosure - Segment Reporting - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SegmentReportingAdditionalInformationDetail</Role>
      <ShortName>Segment Reporting - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>165</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R166.htm</HtmlFileName>
      <LongName>1166 - Disclosure - Segment Reporting - Summary of Operating Segments (Income Statement) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SegmentReportingSummaryOfOperatingSegmentsIncomeStatementDetail</Role>
      <ShortName>Segment Reporting - Summary of Operating Segments (Income Statement) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>166</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R167.htm</HtmlFileName>
      <LongName>1167 - Disclosure - Segment Reporting - Summary of Operating Segments ( Balance Sheet ) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/SegmentReportingSummaryOfOperatingSegmentsBalanceSheetDetail</Role>
      <ShortName>Segment Reporting - Summary of Operating Segments ( Balance Sheet ) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>167</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R168.htm</HtmlFileName>
      <LongName>1168 - Disclosure - Capital Management and Risk Policies - Summary of Regulatory Capital (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfRegulatoryCapitalDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Regulatory Capital (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>168</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R169.htm</HtmlFileName>
      <LongName>1169 - Disclosure - Capital Management and Risk Policies - Summary of Breakdown of Minimum Capital Requirement (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfBreakdownOfMinimumCapitalRequirementDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Breakdown of Minimum Capital Requirement (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>169</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R170.htm</HtmlFileName>
      <LongName>1170 - Disclosure - Capital Management and Risk Policies - Summary of Estimated Risk for Each Type of Instrument (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfEstimatedRiskForEachTypeOfInstrumentDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Estimated Risk for Each Type of Instrument (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>170</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R171.htm</HtmlFileName>
      <LongName>1171 - Disclosure - Capital Management and Risk Policies - Summary of Exposure to Foreign Exchange Risk as of Year End by Type of Currency (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfExposureToForeignExchangeRiskAsOfYearEndByTypeOfCurrencyDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Exposure to Foreign Exchange Risk as of Year End by Type of Currency (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>171</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R172.htm</HtmlFileName>
      <LongName>1172 - Disclosure - Capital Management and Risk Policies - Summary of Exposure to Foreign Exchange Risk as of Year End by Change in Type of Currency (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfExposureToForeignExchangeRiskAsOfYearEndByChangeInTypeOfCurrencyDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Exposure to Foreign Exchange Risk as of Year End by Change in Type of Currency (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>172</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R173.htm</HtmlFileName>
      <LongName>1173 - Disclosure - Capital Management and Risk Policies - Schedule of Residual Value of Assets and Liabilities, Classified by Interest Renegotiation Date or Maturity Date (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesScheduleOfResidualValueOfAssetsAndLiabilitiesClassifiedByInterestRenegotiationDateOrMaturityDateDetail</Role>
      <ShortName>Capital Management and Risk Policies - Schedule of Residual Value of Assets and Liabilities, Classified by Interest Renegotiation Date or Maturity Date (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>173</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R174.htm</HtmlFileName>
      <LongName>1174 - Disclosure - Capital Management and Risk Policies - Schedule of Sensitivity to Potential Additional Changes in Interest Rates (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesScheduleOfSensitivityToPotentialAdditionalChangesInInterestRatesDetail</Role>
      <ShortName>Capital Management and Risk Policies - Schedule of Sensitivity to Potential Additional Changes in Interest Rates (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>174</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R175.htm</HtmlFileName>
      <LongName>1175 - Disclosure - Capital Management and Risk Policies - Schedule of Analysis of Maturities of Assets and Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesScheduleOfAnalysisOfMaturitiesOfAssetsAndLiabilitiesDetail</Role>
      <ShortName>Capital Management and Risk Policies - Schedule of Analysis of Maturities of Assets and Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>175</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R176.htm</HtmlFileName>
      <LongName>1176 - Disclosure - Capital Management and Risk Policies - Schedule of Credit Quality of Debt Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesScheduleOfCreditQualityOfDebtSecuritiesDetail</Role>
      <ShortName>Capital Management and Risk Policies - Schedule of Credit Quality of Debt Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>176</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R177.htm</HtmlFileName>
      <LongName>1177 - Disclosure - Capital Management and Risk Policies - Summary of Retail Portfolios (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfRetailPortfoliosDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Retail Portfolios (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>177</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R178.htm</HtmlFileName>
      <LongName>1178 - Disclosure - Capital Management and Risk Policies - Additional information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesAdditionalInformationDetail</Role>
      <ShortName>Capital Management and Risk Policies - Additional information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>178</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R179.htm</HtmlFileName>
      <LongName>1179 - Disclosure - Capital Management and Risk Policies - Summary of key macroeconomic variables (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfKeyMacroeconomicVariablesDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of key macroeconomic variables (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>179</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R180.htm</HtmlFileName>
      <LongName>1180 - Disclosure - Capital Management and Risk Policies - Summary of Scenario Probabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfScenarioProbabilitiesDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Scenario Probabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>180</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R181.htm</HtmlFileName>
      <LongName>1181 - Disclosure - Capital Management and Risk Policies Summary of Sensitivity Analysis to Assess Impact of Volatility on Macroeconomic Variables on Expected Credit Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfSensitivityAnalysisToAssessImpactOfVolatilityOnMacroeconomicVariablesOnExpectedCreditLossesDetail</Role>
      <ShortName>Capital Management and Risk Policies Summary of Sensitivity Analysis to Assess Impact of Volatility on Macroeconomic Variables on Expected Credit Losses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>181</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R182.htm</HtmlFileName>
      <LongName>1182 - Disclosure - Capital Management and Risk Policies - Summary of Maximum Exposure to Credit Risk on Assests (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfMaximumExposureToCreditRiskOnAssestsDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Maximum Exposure to Credit Risk on Assests (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>182</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R183.htm</HtmlFileName>
      <LongName>1183 - Disclosure - Capital Management and Risk Policies - Summary of Information On Balance Sheet Items And Their Collateral In Offsets As Well As Loan And Other Credit - Related Commitments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfInformationOnBalanceSheetItemsAndTheirCollateralInOffsetsAsWellAsLoanAndOtherCreditRelatedCommitmentsDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Information On Balance Sheet Items And Their Collateral In Offsets As Well As Loan And Other Credit - Related Commitments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>183</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R184.htm</HtmlFileName>
      <LongName>1184 - Disclosure - Capital Management and Risk Policies - Summary of Mortgage Portfolio LTV Distribution (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfMortgagePortfolioLtvDistributionDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Mortgage Portfolio LTV Distribution (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>184</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R185.htm</HtmlFileName>
      <LongName>1185 - Disclosure - Capital Management and Risk Policies - Summary of Changes in Loss Allowance Between Beginning and End of Annual Period (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesSummaryOfChangesInLossAllowanceBetweenBeginningAndEndOfAnnualPeriodDetail</Role>
      <ShortName>Capital Management and Risk Policies - Summary of Changes in Loss Allowance Between Beginning and End of Annual Period (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>185</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R186.htm</HtmlFileName>
      <LongName>1186 - Disclosure - Capital Management and Risk Policies - Schedule of Changes in Gross Carrying Amount of Specific Segment Portfolio (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/CapitalManagementAndRiskPoliciesScheduleOfChangesInGrossCarryingAmountOfSpecificSegmentPortfolioDetail</Role>
      <ShortName>Capital Management and Risk Policies - Schedule of Changes in Gross Carrying Amount of Specific Segment Portfolio (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>186</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R187.htm</HtmlFileName>
      <LongName>1187 - Disclosure - Contingencies and Commitments - Summary of Provisions for Contingencies (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/ContingenciesAndCommitmentsSummaryOfProvisionsForContingenciesDetail</Role>
      <ShortName>Contingencies and Commitments - Summary of Provisions for Contingencies (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>187</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R188.htm</HtmlFileName>
      <LongName>1188 - Disclosure - Offsetting of Financial Assets and Liabilities - Summary of Financial Instruments Subject to Offsetting, Master Netting Agreements and Similar Agreements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffsettingOfFinancialAssetsAndLiabilitiesSummaryOfFinancialInstrumentsSubjectToOffsettingMasterNettingAgreementsAndSimilarAgreementsDetail</Role>
      <ShortName>Offsetting of Financial Assets and Liabilities - Summary of Financial Instruments Subject to Offsetting, Master Netting Agreements and Similar Agreements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>188</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R189.htm</HtmlFileName>
      <LongName>1189 - Disclosure - Off-balance Sheet Items - Schedule of Credit Exposure (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsScheduleOfCreditExposureDetail</Role>
      <ShortName>Off-balance Sheet Items - Schedule of Credit Exposure (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>189</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R190.htm</HtmlFileName>
      <LongName>1190 - Disclosure - Off-balance Sheet Items - Schedule of Fees and Commissions Related to Credit Exposure (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsScheduleOfFeesAndCommissionsRelatedToCreditExposureDetail</Role>
      <ShortName>Off-balance Sheet Items - Schedule of Fees and Commissions Related to Credit Exposure (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>190</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R191.htm</HtmlFileName>
      <LongName>1191 - Disclosure - Off-balance Sheet Items - Schedule of Counter-guarantees, Classified by Type (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsScheduleOfCounterGuaranteesClassifiedByTypeDetail</Role>
      <ShortName>Off-balance Sheet Items - Schedule of Counter-guarantees, Classified by Type (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>191</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R192.htm</HtmlFileName>
      <LongName>1192 - Disclosure - Off-balance Sheet Items - Schedule of Credit Risk by Probability of Default (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsScheduleOfCreditRiskByProbabilityOfDefaultDetail</Role>
      <ShortName>Off-balance Sheet Items - Schedule of Credit Risk by Probability of Default (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>192</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R193.htm</HtmlFileName>
      <LongName>1193 - Disclosure - Off-balance Sheet Items - Schedule of Amounts of Trust Funds and Securities Held in Custody (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/OffBalanceSheetItemsScheduleOfAmountsOfTrustFundsAndSecuritiesHeldInCustodyDetail</Role>
      <ShortName>Off-balance Sheet Items - Schedule of Amounts of Trust Funds and Securities Held in Custody (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>193</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R194.htm</HtmlFileName>
      <LongName>1194 - Disclosure - Non-controlling Interest - Summary of Non-controlling Equity Investment Percentages and Votes (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonControllingInterestSummaryOfNonControllingEquityInvestmentPercentagesAndVotesDetail</Role>
      <ShortName>Non-controlling Interest - Summary of Non-controlling Equity Investment Percentages and Votes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>194</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R195.htm</HtmlFileName>
      <LongName>1195 - Disclosure - Non-controlling Interest - Summary of Movements in Group's Significant Non-Controlling Interests (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/NonControllingInterestSummaryOfMovementsInGroupsSignificantNonControllingInterestsDetail</Role>
      <ShortName>Non-controlling Interest - Summary of Movements in Group's Significant Non-Controlling Interests (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>195</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R196.htm</HtmlFileName>
      <LongName>1196 - Disclosure - Related Party Transactions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactionsAdditionalInformationDetail</Role>
      <ShortName>Related Party Transactions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>196</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R197.htm</HtmlFileName>
      <LongName>1197 - Disclosure - Related Party Transactions - Summary of Controlled Entity of Related Party Transactions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactionsSummaryOfControlledEntityOfRelatedPartyTransactionsDetail</Role>
      <ShortName>Related Party Transactions - Summary of Controlled Entity of Related Party Transactions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>197</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R198.htm</HtmlFileName>
      <LongName>1198 - Disclosure - Related Party Disclosures - Compensation of Key Management Personnel (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyDisclosuresCompensationOfKeyManagementPersonnelDetail</Role>
      <ShortName>Related Party Disclosures - Compensation of Key Management Personnel (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>198</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R199.htm</HtmlFileName>
      <LongName>1199 - Disclosure - Related Party Transactions - Summary of Total Assistance Granted by Group to Key Personnel, Syndics, Majority Shareholders, as well as all Individuals (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactionsSummaryOfTotalAssistanceGrantedByGroupToKeyPersonnelSyndicsMajorityShareholdersAsWellAsAllIndividualsDetail</Role>
      <ShortName>Related Party Transactions - Summary of Total Assistance Granted by Group to Key Personnel, Syndics, Majority Shareholders, as well as all Individuals (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>199</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R200.htm</HtmlFileName>
      <LongName>1200 - Disclosure - Related Party Transactions - Summary of Amounts of Related Party Transactions (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/RelatedPartyTransactionsSummaryOfAmountsOfRelatedPartyTransactionsDetail</Role>
      <ShortName>Related Party Transactions - Summary of Amounts of Related Party Transactions (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>200</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R201.htm</HtmlFileName>
      <LongName>1201 - Disclosure - Acquisition of Debt Securities Under Section 35 BIS of Financial Institutions Law - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AcquisitionOfDebtSecuritiesUnderSection35BisOfFinancialInstitutionsLawAdditionalInformationDetail</Role>
      <ShortName>Acquisition of Debt Securities Under Section 35 BIS of Financial Institutions Law - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>201</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R202.htm</HtmlFileName>
      <LongName>1202 - Disclosure - Additional Information Required by the Argentine Central Bank - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankAdditionalInformationDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>202</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R203.htm</HtmlFileName>
      <LongName>1203 - Disclosure - Additional Information Required by the Argentine Central Bank - Cash and Government Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankCashAndGovernmentSecuritiesDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Cash and Government Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>203</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R204.htm</HtmlFileName>
      <LongName>1204 - Disclosure - Additional Information Required by the Argentine Central Bank - Special Guarantees Accounts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSpecialGuaranteesAccountsDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Special Guarantees Accounts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>204</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R205.htm</HtmlFileName>
      <LongName>1205 - Disclosure - Additional Information Required by the Argentine Central Bank - Deposits in favor of the Argentine Central Bank (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankDepositsInFavorOfTheArgentineCentralBankDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Deposits in favor of the Argentine Central Bank (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>205</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R206.htm</HtmlFileName>
      <LongName>1206 - Disclosure - Additional Information Required by the Argentine Central Bank - Contributions to Garantizar S.G.R.'s Risk Fund (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankContributionsToGarantizarSGRSRiskFundDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Contributions to Garantizar S.G.R.'s Risk Fund (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>206</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R207.htm</HtmlFileName>
      <LongName>1207 - Disclosure - Additional Information Required by the Argentine Central Bank - Financial Assets as Collateral for Loans Borrowed as First Pledges (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankFinancialAssetsAsCollateralForLoansBorrowedAsFirstPledgesDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Financial Assets as Collateral for Loans Borrowed as First Pledges (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>207</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R208.htm</HtmlFileName>
      <LongName>1208 - Disclosure - Additional Information Required by the Argentine Central Bank - Financial Assets as Collateral for Loans Borrowed as First Pledges (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankFinancialAssetsAsCollateralForLoansBorrowedAsFirstPledgesParentheticalDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Financial Assets as Collateral for Loans Borrowed as First Pledges (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>208</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R209.htm</HtmlFileName>
      <LongName>1209 - Disclosure - Additional Information Required by the Argentine Central Bank - Additional Information 2 (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankAdditionalInformation2Detail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Additional Information 2 (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>209</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R210.htm</HtmlFileName>
      <LongName>1210 - Disclosure - Additional Information Required by the Argentine Central Bank - Summary of Fiduciary Property Breakdown (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSummaryOfFiduciaryPropertyBreakdownDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Summary of Fiduciary Property Breakdown (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>210</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R211.htm</HtmlFileName>
      <LongName>1211 - Disclosure - Additional Information Required by the Argentine Central Bank - Summary of Financial Trust Contracts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSummaryOfFinancialTrustContractsDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Summary of Financial Trust Contracts (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>211</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R212.htm</HtmlFileName>
      <LongName>1212 - Disclosure - Additional Information Required by the Argentine Central Bank - Summary of Balances of the Mutual Funds (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSummaryOfBalancesOfTheMutualFundsDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Summary of Balances of the Mutual Funds (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>212</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R213.htm</HtmlFileName>
      <LongName>1213 - Disclosure - Additional Information Required by the Argentine Central Bank - Summary of Compliance with Minimum Cash Requirements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSummaryOfComplianceWithMinimumCashRequirementsDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Summary of Compliance with Minimum Cash Requirements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>213</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R214.htm</HtmlFileName>
      <LongName>1214 - Disclosure - Additional Information Required by the Argentine Central Bank - Summary of Compliance with Minimum Cash Requirements (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankSummaryOfComplianceWithMinimumCashRequirementsParentheticalDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Summary of Compliance with Minimum Cash Requirements (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>214</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R215.htm</HtmlFileName>
      <LongName>1215 - Disclosure - Additional Information Required by the Argentine Central Bank - Schedule of Shareholders' Equity (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankScheduleOfShareholdersEquityDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Schedule of Shareholders' Equity (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>215</Position>
    </Report>
    <Report instance="ggal-20191231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R216.htm</HtmlFileName>
      <LongName>1216 - Disclosure - Additional Information Required by the Argentine Central Bank - Schedule of Plan for Distribution of Profit (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gfgsa.com/role/AdditionalInformationRequiredByTheArgentineCentralBankScheduleOfPlanForDistributionOfProfitDetail</Role>
      <ShortName>Additional Information Required by the Argentine Central Bank - Schedule of Plan for Distribution of Profit (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>216</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ggal-20191231.xml</File>
    <File>ggal-20191231.xsd</File>
    <File>ggal-20191231_cal.xml</File>
    <File>ggal-20191231_def.xml</File>
    <File>ggal-20191231_lab.xml</File>
    <File>ggal-20191231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.ifrs.org/taxonomy/2019-03-27/ifrs-full</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/currency/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
