<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.1.1.u2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>134</ContextCount>
  <ElementCount>282</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>55</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="kplt-20240331.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-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0000002 - 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-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0000003 - 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-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0000004 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSS</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0000005 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS??? DEFICIT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSDEFICIT</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS??? DEFICIT</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0000006 - 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-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0000007 - 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-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0000008 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatements</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0000009 - 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>9</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0000010 - 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>10</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0000011 - Disclosure - Property and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyandEquipmentNet</Role>
      <ShortName>Property and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0000012 - Disclosure - Capitalized Software and Intangible Assets, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNet</Role>
      <ShortName>Capitalized Software and Intangible Assets, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0000013 - Disclosure - Accrued Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/AccruedLiabilities</Role>
      <ShortName>Accrued Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0000014 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/Debt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0000015 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0000016 - 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>16</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>0000017 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>0000018 - Disclosure - Net Loss Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NetLossPerShare</Role>
      <ShortName>Net Loss Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>0000019 - 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>19</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>0000020 - 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>20</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>0000021 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.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>22</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.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>23</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>9954471 - 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>
      <ParentRole>http://www.katapult.com/role/SummaryofSignificantAccountingPolicies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>9954472 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsTables</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatements</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>9954473 - 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>26</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>9954474 - 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>27</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>9954475 - Disclosure - Property and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyandEquipmentNetTables</Role>
      <ShortName>Property and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/PropertyandEquipmentNet</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>9954476 - Disclosure - Capitalized Software and Intangible Assets, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNetTables</Role>
      <ShortName>Capitalized Software and Intangible Assets, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNet</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>9954477 - 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>30</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>9954478 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/Debt</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>9954479 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/Leases</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>9954480 - 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>33</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>9954481 - Disclosure - Net Loss Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NetLossPerShareTables</Role>
      <ShortName>Net Loss Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.katapult.com/role/NetLossPerShare</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>9954482 - 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>35</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>9954483 - 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>36</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>9954484 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsNarrativeDetails</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>9954485 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Balance Sheet (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsCondensedConsolidatedBalanceSheetDetails</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Balance Sheet (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>9954486 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Statement of Operations and Comprehensive Loss (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsCondensedConsolidatedStatementofOperationsandComprehensiveLossDetails</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Statement of Operations and Comprehensive Loss (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>9954487 - Disclosure - Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Statement of Cash Flow (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/RestatementofPreviouslyIssuedUnauditedInterimCondensedConsolidatedFinancialStatementsCondensedConsolidatedStatementofCashFlowDetails</Role>
      <ShortName>Restatement of Previously Issued Unaudited Interim Condensed Consolidated Financial Statements - Condensed Consolidated Statement of Cash Flow (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>9954488 - 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>41</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>9954489 - Disclosure - Summary of Significant Accounting Policies - Summary of Reconciliation of Cash and Restricted Cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SummaryofSignificantAccountingPoliciesSummaryofReconciliationofCashandRestrictedCashDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Summary of Reconciliation of Cash and Restricted Cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>9954490 - Disclosure - Summary of Significant Accounting Policies - Summary of Useful Lives (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/SummaryofSignificantAccountingPoliciesSummaryofUsefulLivesDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Summary of Useful Lives (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>9954491 - Disclosure - Property Held for Lease, Net of Accumulated Depreciation and Impairment- Summary of Property Held for Lease, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyHeldforLeaseNetofAccumulatedDepreciationandImpairmentSummaryofPropertyHeldforLeaseNetDetails</Role>
      <ShortName>Property Held for Lease, Net of Accumulated Depreciation and Impairment- Summary of Property Held for Lease, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>9954492 - Disclosure - Property Held for Lease, Net of Accumulated Depreciation and Impairment- Summary of Property Subject to or Available for Operating Lease, Cost of Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyHeldforLeaseNetofAccumulatedDepreciationandImpairmentSummaryofPropertySubjecttoorAvailableforOperatingLeaseCostofRevenueDetails</Role>
      <ShortName>Property Held for Lease, Net of Accumulated Depreciation and Impairment- Summary of Property Subject to or Available for Operating Lease, Cost of Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>9954493 - Disclosure - Property and Equipment, Net - Summary of Property and Equipment, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyandEquipmentNetSummaryofPropertyandEquipmentNetDetails</Role>
      <ShortName>Property and Equipment, Net - Summary of Property and Equipment, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>9954494 - Disclosure - Property and Equipment, Net - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/PropertyandEquipmentNetNarrativeDetails</Role>
      <ShortName>Property and Equipment, Net - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>9954495 - Disclosure - Capitalized Software and Intangible Assets, Net - Summary of Capitalized Software and Intangible Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNetSummaryofCapitalizedSoftwareandIntangibleAssetsDetails</Role>
      <ShortName>Capitalized Software and Intangible Assets, Net - Summary of Capitalized Software and Intangible Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>9954496 - Disclosure - Capitalized Software and Intangible Assets, Net - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNetNarrativeDetails</Role>
      <ShortName>Capitalized Software and Intangible Assets, Net - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>9954497 - Disclosure - Capitalized Software and Intangible Assets, Net - Summary of Estimated Future Amortization Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/CapitalizedSoftwareandIntangibleAssetsNetSummaryofEstimatedFutureAmortizationExpenseDetails</Role>
      <ShortName>Capitalized Software and Intangible Assets, Net - Summary of Estimated Future Amortization Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>9954498 - 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>51</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>9954499 - Disclosure - Debt- Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DebtNarrativeDetails</Role>
      <ShortName>Debt- Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>9954500 - Disclosure - Debt - Summary of Borrowings Outstanding (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DebtSummaryofBorrowingsOutstandingDetails</Role>
      <ShortName>Debt - Summary of Borrowings Outstanding (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>9954501 - Disclosure - Debt - Summary of Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/DebtSummaryofDebtDetails</Role>
      <ShortName>Debt - Summary of Debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>9954502 - Disclosure - Leases - Summary of Future Minimum Lease Payments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/LeasesSummaryofFutureMinimumLeasePaymentsDetails</Role>
      <ShortName>Leases - Summary of Future Minimum Lease Payments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>9954503 - Disclosure - Leases - Summary of Lease Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/LeasesSummaryofLeaseLiabilitiesDetails</Role>
      <ShortName>Leases - Summary of Lease Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>9954504 - Disclosure - Leases - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/LeasesNarrativeDetails</Role>
      <ShortName>Leases - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>9954505 - 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>58</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>9954506 - Disclosure - Stock-Based Compensation - Summary of Stock Options (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/StockBasedCompensationSummaryofStockOptionsDetails</Role>
      <ShortName>Stock-Based Compensation - Summary of Stock Options (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>9954507 - Disclosure - Stock-Based Compensation - Summary of RSUs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/StockBasedCompensationSummaryofRSUsDetails</Role>
      <ShortName>Stock-Based Compensation - Summary of RSUs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>9954508 - 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>61</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>9954509 - Disclosure - Net Loss Per Share - Narrative (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NetLossPerShareNarrativeDetails</Role>
      <ShortName>Net Loss Per Share - Narrative (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>9954510 - Disclosure - Net Loss Per Share - Schedule of Antidilutive Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/NetLossPerShareScheduleofAntidilutiveSecuritiesDetails</Role>
      <ShortName>Net Loss Per Share - Schedule of Antidilutive Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>9954511 - 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>64</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>9954512 - Disclosure - Fair Value Measurements - Summary of Fair Values (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FairValueMeasurementsSummaryofFairValuesDetails</Role>
      <ShortName>Fair Value Measurements - Summary of Fair Values (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>9954513 - Disclosure - Fair Value Measurements - Summary of Liabilities Measured on a Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FairValueMeasurementsSummaryofLiabilitiesMeasuredonaRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements - Summary of Liabilities Measured on a Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="kplt-20240331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>9954514 - Disclosure - Fair Value Measurements - Summary of Warrant Liability Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.katapult.com/role/FairValueMeasurementsSummaryofWarrantLiabilityActivityDetails</Role>
      <ShortName>Fair Value Measurements - Summary of Warrant Liability Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Warning">[ix-0514-Hidden-Fact-Eligible-For-Transform] WARN: 4 fact(s) appearing in ix:hidden were eligible for transformation: kplt:ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantRatio, us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1, us-gaap:StockholdersEquityNoteStockSplitConversionRatio1 -  kplt-20240331.htm 4</Log>
  </Logs>
  <InputFiles>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="kplt-20240331.htm">kplt-20240331.htm</File>
    <File>kplt-20240331.xsd</File>
    <File>kplt-20240331_cal.xml</File>
    <File>kplt-20240331_def.xml</File>
    <File>kplt-20240331_lab.xml</File>
    <File>kplt-20240331_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="573">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="33">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
