<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>311</ContextCount>
  <ElementCount>224</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>74</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>001 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConsolidatedBalanceSheet</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>002 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConsolidatedBalanceSheet_Parentheticals</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>003 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConsolidatedIncomeStatement</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>004 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConsolidatedCashFlow</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>005 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ShareholdersEquityType2or3</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>006 - Disclosure - Basis of Presentation and Liquidity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/BasisofPresentationandLiquidity</Role>
      <ShortName>Basis of Presentation and Liquidity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>007 - Disclosure - Accrued Expenses and Other</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/AccruedExpensesandOther</Role>
      <ShortName>Accrued Expenses and Other</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>008 - Disclosure - Convertible Notes Payable ??? Related Party</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://galectintherapeutics.com/role/ConvertibleNotesPayableRelatedParty</Role>
      <ShortName>Convertible Notes Payable ??? Related Party</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>009 - Disclosure - Fair Value of Financial Instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/FairValueofFinancialInstruments</Role>
      <ShortName>Fair Value of Financial Instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>010 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/StockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>011 - Disclosure - Common Stock Warrants</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStockWarrants</Role>
      <ShortName>Common Stock Warrants</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>012 - Disclosure - Loss Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/LossPerShare</Role>
      <ShortName>Loss Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>013 - Disclosure - Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStock</Role>
      <ShortName>Common Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>014 - Disclosure - Convertible Line of Credit - Related Party and Supplemental Convertible Lines of Credit - Related Party</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConvertibleLineofCreditRelatedPartyandSupplementalConvertibleLinesofCreditRelatedParty</Role>
      <ShortName>Convertible Line of Credit - Related Party and Supplemental Convertible Lines of Credit - Related Party</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>015 - Disclosure - Segments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/Segments</Role>
      <ShortName>Segments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>016 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommitmentsandContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>017 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>018 - Disclosure - Galectin Sciences LLC</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/GalectinSciencesLLC</Role>
      <ShortName>Galectin Sciences LLC</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>996000 - Disclosure - Accrued Expenses and Other (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/AccruedExpensesandOtherTables</Role>
      <ShortName>Accrued Expenses and Other (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/AccruedExpensesandOther</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>996001 - Disclosure - Fair Value of Financial Instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/FairValueofFinancialInstrumentsTables</Role>
      <ShortName>Fair Value of Financial Instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/FairValueofFinancialInstruments</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>996002 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/StockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/StockBasedCompensation</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>996003 - Disclosure - Common Stock Warrants (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStockWarrantsTables</Role>
      <ShortName>Common Stock Warrants (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/CommonStockWarrants</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>996004 - Disclosure - Loss Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/LossPerShareTables</Role>
      <ShortName>Loss Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/LossPerShare</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Segments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/SegmentsTables</Role>
      <ShortName>Segments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/Segments</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>996006 - Disclosure - Basis of Presentation and Liquidity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/BasisofPresentationandLiquidityDetails</Role>
      <ShortName>Basis of Presentation and Liquidity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/BasisofPresentationandLiquidity</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>996007 - Disclosure - Accrued Expenses and Other - Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/AccruedExpensesTable</Role>
      <ShortName>Accrued Expenses and Other - Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>996008 - Disclosure - Convertible Notes Payable ??? Related Party (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://galectintherapeutics.com/role/ConvertibleNotesPayableRelatedPartyDetails</Role>
      <ShortName>Convertible Notes Payable ??? Related Party (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/ConvertibleNotesPayableRelatedParty</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>996009 - Disclosure - Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/FairValueofFinancialInstrumentsDetails</Role>
      <ShortName>Fair Value of Financial Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/FairValueofFinancialInstrumentsTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>996010 - Disclosure - Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/AssetsandLiabilitiesMeasuredandRecordedatFairValueonRecurringBasisTable</Role>
      <ShortName>Fair Value of Financial Instruments - Assets and Liabilities Measured and Recorded at Fair Value on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>996011 - Disclosure - Fair Value of Financial Instruments - April Note, Key Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/AprilNoteKeyAssumptionsTable</Role>
      <ShortName>Fair Value of Financial Instruments - April Note, Key Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>996012 - Disclosure - Fair Value of Financial Instruments - Roll Forward of April Note Derivative Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/RollForwardofAprilNoteDerivativeLiabilityTable</Role>
      <ShortName>Fair Value of Financial Instruments - Roll Forward of April Note Derivative Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>996013 - Disclosure - Fair Value of Financial Instruments - September Note, Key Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/SeptemberNoteKeyAssumptionsTable</Role>
      <ShortName>Fair Value of Financial Instruments - September Note, Key Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>996014 - Disclosure - Fair Value of Financial Instruments - Roll Forward of September Note Derivative Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/RollForwardofSeptemberNoteDerivativeLiabilityTable</Role>
      <ShortName>Fair Value of Financial Instruments - Roll Forward of September Note Derivative Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Fair Value of Financial Instruments - December Note, Key Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/DecemberNoteKeyAssumptionsTable</Role>
      <ShortName>Fair Value of Financial Instruments - December Note, Key Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>996016 - Disclosure - Fair Value of Financial Instruments - Roll Forward of December Note Derivative Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/RollForwardofDecemberNoteDerivativeLiabilityTable</Role>
      <ShortName>Fair Value of Financial Instruments - Roll Forward of December Note Derivative Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>996017 - Disclosure - Stock-Based Compensation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/StockBasedCompensationDetails</Role>
      <ShortName>Stock-Based Compensation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/StockBasedCompensationTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>996018 - Disclosure - Stock-Based Compensation - Components of Stock-Based Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ComponentsofStockBasedCompensationExpenseTable</Role>
      <ShortName>Stock-Based Compensation - Components of Stock-Based Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>996019 - Disclosure - Stock-Based Compensation - Stock Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/StockOptionActivityTable</Role>
      <ShortName>Stock-Based Compensation - Stock Option Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>996020 - Disclosure - Stock-Based Compensation - Weighted Average Assumptions Used to Determine Fair Value of Options Granted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/WeightedAverageAssumptionsUsedtoDetermineFairValueofOptionsGrantedTable</Role>
      <ShortName>Stock-Based Compensation - Weighted Average Assumptions Used to Determine Fair Value of Options Granted (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>996021 - Disclosure - Common Stock Warrants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStockWarrantsDetails</Role>
      <ShortName>Common Stock Warrants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/CommonStockWarrantsTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>996022 - Disclosure - Common Stock Warrants - Common Stock Warrants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStockWarrantsTable</Role>
      <ShortName>Common Stock Warrants - Common Stock Warrants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>996023 - Disclosure - Loss Per Share - Loss Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/LossPerShareTable</Role>
      <ShortName>Loss Per Share - Loss Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>996024 - Disclosure - Common Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommonStockDetails</Role>
      <ShortName>Common Stock (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/CommonStockWarrantsTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>996025 - Disclosure - Convertible Line of Credit - Related Party and Supplemental Convertible Lines of Credit - Related Party (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/ConvertibleLineofCreditRelatedPartyandSupplementalConvertibleLinesofCreditRelatedPartyDetails</Role>
      <ShortName>Convertible Line of Credit - Related Party and Supplemental Convertible Lines of Credit - Related Party (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/ConvertibleLineofCreditRelatedPartyandSupplementalConvertibleLinesofCreditRelatedParty</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>996026 - Disclosure - Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/SegmentsDetails</Role>
      <ShortName>Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/SegmentsTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>996027 - Disclosure - Segments - Significant Expense and Asset Categories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/SignificantExpenseandAssetCategoriesTable</Role>
      <ShortName>Segments - Significant Expense and Asset Categories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>996028 - Disclosure - Commitments and Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/CommitmentsandContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/CommitmentsandContingencies</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>996029 - Disclosure - Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/LeasesDetails</Role>
      <ShortName>Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/Leases</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="ef20070490_10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>996030 - Disclosure - Galectin Sciences LLC (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://galectintherapeutics.com/role/GalectinSciencesLLCDetails</Role>
      <ShortName>Galectin Sciences LLC (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://galectintherapeutics.com/role/GalectinSciencesLLC</ParentRole>
      <Position>52</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="ef20070490_10q.htm">ef20070490_10q.htm</File>
    <File>galt-20260331.xsd</File>
    <File>galt-20260331_cal.xml</File>
    <File>galt-20260331_def.xml</File>
    <File>galt-20260331_lab.xml</File>
    <File>galt-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="648">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="2">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
