<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>126</ContextCount>
  <ElementCount>240</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>49</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>11</UnitCount>
  <MyReports>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0000001 - Document - Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/Cover</Role>
      <ShortName>Cover</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>9952151 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>9952152 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDBALANCESHEETSParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>9952153 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>9952154 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF MEZZANINE EQUITY AND STOCKHOLDERS??? DEFICIT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFMEZZANINEEQUITYANDSTOCKHOLDERSDEFICIT</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF MEZZANINE EQUITY AND STOCKHOLDERS??? DEFICIT</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>9952155 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>9952156 - Disclosure - DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DESCRIPTIONOFBUSINESSANDBASISOFPRESENTATION</Role>
      <ShortName>DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>9952157 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>9952158 - Disclosure - PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PROPERTYHELDFORLEASENETOFACCUMULATEDDEPRECIATIONANDIMPAIRMENT</Role>
      <ShortName>PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>9952159 - Disclosure - ACCRUED LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/ACCRUEDLIABILITIES</Role>
      <ShortName>ACCRUED LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>9952160 - Disclosure - DEBT &amp; LIQUIDITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DEBTLIQUIDITY</Role>
      <ShortName>DEBT &amp; LIQUIDITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>9952161 - Disclosure - MEZZANINE EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/MEZZANINEEQUITY</Role>
      <ShortName>MEZZANINE EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>9952162 - Disclosure - STOCK-BASED COMPENSATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/STOCKBASEDCOMPENSATION</Role>
      <ShortName>STOCK-BASED COMPENSATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>9952163 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>9952164 - Disclosure - NET INCOME (LOSS) PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NETINCOMELOSSPERSHARE</Role>
      <ShortName>NET INCOME (LOSS) PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>9952165 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/COMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>9952166 - Disclosure - FAIR VALUE MEASUREMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTS</Role>
      <ShortName>FAIR VALUE MEASUREMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>9952167 - Disclosure - SEGMENT REPORTING</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SEGMENTREPORTING</Role>
      <ShortName>SEGMENT REPORTING</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>9952168 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUBSEQUENTEVENTS</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.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>20</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>9955511 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>9955512 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESTables</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIES</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>9955513 - Disclosure - PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PROPERTYHELDFORLEASENETOFACCUMULATEDDEPRECIATIONANDIMPAIRMENTTables</Role>
      <ShortName>PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/PROPERTYHELDFORLEASENETOFACCUMULATEDDEPRECIATIONANDIMPAIRMENT</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9955514 - Disclosure - ACCRUED LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/ACCRUEDLIABILITIESTables</Role>
      <ShortName>ACCRUED LIABILITIES (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/ACCRUEDLIABILITIES</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9955515 - Disclosure - STOCK-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/STOCKBASEDCOMPENSATIONTables</Role>
      <ShortName>STOCK-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/STOCKBASEDCOMPENSATION</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9955516 - Disclosure - NET INCOME (LOSS) PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NETINCOMELOSSPERSHARETables</Role>
      <ShortName>NET INCOME (LOSS) PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/NETINCOMELOSSPERSHARE</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9955517 - Disclosure - FAIR VALUE MEASUREMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSTables</Role>
      <ShortName>FAIR VALUE MEASUREMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/FAIRVALUEMEASUREMENTS</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9955518 - Disclosure - DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DESCRIPTIONOFBUSINESSANDBASISOFPRESENTATIONDetails</Role>
      <ShortName>DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/DESCRIPTIONOFBUSINESSANDBASISOFPRESENTATION</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9955519 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESNarrativeDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9955520 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Reconciliation of Cash and Restricted Cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SUMMARYOFSIGNIFICANTACCOUNTINGPOLICIESScheduleofReconciliationofCashandRestrictedCashDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Reconciliation of Cash and Restricted Cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9955521 - Disclosure - PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT - Schedule of Property Held for Lease, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PROPERTYHELDFORLEASENETOFACCUMULATEDDEPRECIATIONANDIMPAIRMENTScheduleofPropertyHeldforLeaseNetDetails</Role>
      <ShortName>PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT - Schedule of Property Held for Lease, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9955522 - Disclosure - PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT - Schedule of Cost of Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PROPERTYHELDFORLEASENETOFACCUMULATEDDEPRECIATIONANDIMPAIRMENTScheduleofCostofRevenueDetails</Role>
      <ShortName>PROPERTY HELD FOR LEASE, NET OF ACCUMULATED DEPRECIATION AND IMPAIRMENT - Schedule of Cost of Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9955523 - Disclosure - ACCRUED LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/ACCRUEDLIABILITIESDetails</Role>
      <ShortName>ACCRUED LIABILITIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/ACCRUEDLIABILITIESTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9955524 - Disclosure - DEBT &amp; LIQUIDITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DEBTLIQUIDITYDetails</Role>
      <ShortName>DEBT &amp; LIQUIDITY (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/DEBTLIQUIDITY</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9955525 - Disclosure - MEZZANINE EQUITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/MEZZANINEEQUITYDetails</Role>
      <ShortName>MEZZANINE EQUITY (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/MEZZANINEEQUITY</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9955526 - Disclosure - STOCK-BASED COMPENSATION - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/STOCKBASEDCOMPENSATIONNarrativeDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9955527 - Disclosure - STOCK-BASED COMPENSATION - Schedule of Stock Options Under the 2014 Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/STOCKBASEDCOMPENSATIONScheduleofStockOptionsUnderthe2014PlanDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION - Schedule of Stock Options Under the 2014 Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9955528 - Disclosure - STOCK-BASED COMPENSATION - Schedule of RSA Activity Under the 2021 Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/STOCKBASEDCOMPENSATIONScheduleofRSAActivityUnderthe2021PlanDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION - Schedule of RSA Activity Under the 2021 Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9955529 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/INCOMETAXESDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/INCOMETAXES</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9955530 - Disclosure - NET INCOME (LOSS) PER SHARE - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NETINCOMELOSSPERSHARENarrativeDetails</Role>
      <ShortName>NET INCOME (LOSS) PER SHARE - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/NETINCOMELOSSPERSHARETables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9955531 - Disclosure - NET INCOME (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NETINCOMELOSSPERSHAREScheduleofEarningsPerShareBasicandDilutedDetails</Role>
      <ShortName>NET INCOME (LOSS) PER SHARE - Schedule of Earnings Per Share, Basic and Diluted (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/NETINCOMELOSSPERSHARETables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9955532 - Disclosure - NET INCOME (LOSS) PER SHARE - Schedule of Antidilutive Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NETINCOMELOSSPERSHAREScheduleofAntidilutiveSecuritiesDetails</Role>
      <ShortName>NET INCOME (LOSS) PER SHARE - Schedule of Antidilutive Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/NETINCOMELOSSPERSHARETables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9955533 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/COMMITMENTSANDCONTINGENCIESDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/COMMITMENTSANDCONTINGENCIES</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9955534 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of New Revolving Facility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSScheduleofNewRevolvingFacilityDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS - Schedule of New Revolving Facility (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9955535 - Disclosure - FAIR VALUE MEASUREMENTS - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSNarrativeDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9955536 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of Preferred Stock Derivative Liability (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSScheduleofPreferredStockDerivativeLiabilityDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS - Schedule of Preferred Stock Derivative Liability (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9955537 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of Changes in Assumption at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSScheduleofChangesinAssumptionatFairValueDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS - Schedule of Changes in Assumption at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9955538 - Disclosure - FAIR VALUE MEASUREMENTS - Schedule of Warrant Liability Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FAIRVALUEMEASUREMENTSScheduleofWarrantLiabilityActivityDetails</Role>
      <ShortName>FAIR VALUE MEASUREMENTS - Schedule of Warrant Liability Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="kplt-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9955539 - Disclosure - SEGMENT REPORTING (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SEGMENTREPORTINGDetails</Role>
      <ShortName>SEGMENT REPORTING (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/SEGMENTREPORTING</ParentRole>
      <Position>49</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="kplt-20260331.htm">kplt-20260331.htm</File>
    <File>kplt-20260331.xsd</File>
    <File>kplt-20260331_cal.xml</File>
    <File>kplt-20260331_def.xml</File>
    <File>kplt-20260331_lab.xml</File>
    <File>kplt-20260331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="441">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="32">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
