<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>193</ContextCount>
  <ElementCount>315</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>60</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>75000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>75010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_StatementCONDENSEDCONSOLIDATEDBALANCESHEETSUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>75020 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_StatementCONDENSEDCONSOLIDATEDBALANCESHEETSUnauditedParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>75030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONSANDCOMPREHENSIVELOSSUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>75040 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityUnaudited1</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>75060 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_StatementCONDENSEDCONSOLIDATEDSTATEMENTSOFCASHFLOWSUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.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>7</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.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>8</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Organization and Nature of Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureOrganizationAndNatureOfBusiness</Role>
      <ShortName>Organization and Nature of Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Marketable Securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureMarketableSecurities</Role>
      <ShortName>Marketable Securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Collaborations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureCollaborations</Role>
      <ShortName>Collaborations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipment</Role>
      <ShortName>Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureAccruedExpenses</Role>
      <ShortName>Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Other Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureOtherCommitmentsAndContingencies</Role>
      <ShortName>Other Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Equity-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureEquitybasedCompensation1</Role>
      <ShortName>Equity-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Net Loss per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShare</Role>
      <ShortName>Net Loss per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Segment Reporting</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReporting</Role>
      <ShortName>Segment Reporting</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureFairValueMeasurements</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Marketable Securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureMarketableSecuritiesTables</Role>
      <ShortName>Marketable Securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureMarketableSecurities</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Collaborations (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureCollaborationsTables</Role>
      <ShortName>Collaborations (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureCollaborations</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentTables</Role>
      <ShortName>Property and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipment</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeases</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesTables</Role>
      <ShortName>Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureAccruedExpenses</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Equity-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureEquityBasedCompensationTables</Role>
      <ShortName>Equity-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureEquitybasedCompensation1</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Net Loss per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShareTables</Role>
      <ShortName>Net Loss per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShare</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Segment Reporting (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReportingTables</Role>
      <ShortName>Segment Reporting (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReporting</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Organization and Nature of Business - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureOrganizationAndNatureOfBusinessAdditionalInformationDetails</Role>
      <ShortName>Organization and Nature of Business - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfAssetsMeasuredAtFairValueOnRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Fair Value Measurements - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureFairValueMeasurementsAdditionalInformationDetails</Role>
      <ShortName>Fair Value Measurements - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Marketable Securities - Summary of Available-for-Sale Debt Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureMarketableSecuritiesSummaryOfAvailableForSaleDebtSecuritiesDetails</Role>
      <ShortName>Marketable Securities - Summary of Available-for-Sale Debt Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Marketable Securities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureMarketableSecuritiesAdditionalInformationDetails</Role>
      <ShortName>Marketable Securities - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Collaborations - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureCollaborationsAdditionalInformationDetails</Role>
      <ShortName>Collaborations - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Collaborations - Change in Accounts Receivable, Contract Asset and Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureCollaborationsChangeInAccountsReceivableContractAssetAndLiabilitiesDetails</Role>
      <ShortName>Collaborations - Change in Accounts Receivable, Contract Asset and Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Property and Equipment - Summary of Property and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentSummaryOfPropertyAndEquipmentDetails</Role>
      <ShortName>Property and Equipment - Summary of Property and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Property and Equipment - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosurePropertyAndEquipmentAdditionalInformationDetails</Role>
      <ShortName>Property and Equipment - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Leases - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesAdditionalInformationDetails</Role>
      <ShortName>Leases - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Leases - Components of Lease Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesComponentsOfLeaseCostsDetails</Role>
      <ShortName>Leases - Components of Lease Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995845 - Disclosure - Leases - Supplemental Cash Flow Information Relating to Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesSupplementalCashFlowInformationRelatingToLeasesDetails</Role>
      <ShortName>Leases - Supplemental Cash Flow Information Relating to Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995855 - Disclosure - Leases - Summary of Weighted Average Remaining Lease Terms and Discount Rates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesSummaryOfWeightedAverageRemainingLeaseTermsAndDiscountRatesDetails</Role>
      <ShortName>Leases - Summary of Weighted Average Remaining Lease Terms and Discount Rates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Leases - Summary of Undiscounted Future Lease Payments for Operating and Finance Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureLeasesSummaryOfUndiscountedFutureLeasePaymentsForOperatingAndFinanceLeasesDetails</Role>
      <ShortName>Leases - Summary of Undiscounted Future Lease Payments for Operating and Finance Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Accrued Expenses - Schedule of Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesScheduleOfAccruedExpensesDetails</Role>
      <ShortName>Accrued Expenses - Schedule of Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995905 - Disclosure - Other Commitments and Contingencies - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureOtherCommitmentsAndContingenciesAdditionalInformationDetails</Role>
      <ShortName>Other Commitments and Contingencies - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Equity-Based Compensation - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureEquityBasedCompensationAdditionalInformationDetails</Role>
      <ShortName>Equity-Based Compensation - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Equity-Based Compensation - Summary of Stock Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureEquitybasedCompensationSummaryOfStockOptionActivityDetails</Role>
      <ShortName>Equity-Based Compensation - Summary of Stock Option Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Equity-Based Compensation - Summary of Equity-Based Compensation Expense (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureEquityBasedCompensationSummaryOfEquityBasedCompensationExpenseDetails</Role>
      <ShortName>Equity-Based Compensation - Summary of Equity-Based Compensation Expense (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995955 - Disclosure - Equity-Based Compensation - Summary of Weighted-Average Assumptions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureEquityBasedCompensationSummaryOfWeightedAverageAssumptionsDetails</Role>
      <ShortName>Equity-Based Compensation - Summary of Weighted-Average Assumptions (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995965 - Disclosure - Equity-Based Compensation - Summary of Restricted Stock Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureEquityBasedCompensationSummaryOfRestrictedStockActivityDetails</Role>
      <ShortName>Equity-Based Compensation - Summary of Restricted Stock Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995975 - Disclosure - Related Party Transactions - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails</Role>
      <ShortName>Related Party Transactions - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995995 - Disclosure - Net Loss per Share (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureNetLossPerShareAdditionalInformationDetails</Role>
      <ShortName>Net Loss per Share (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShareTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>996005 - Disclosure - Net Loss per Share - Summary of Basic and Diluted Loss Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShareSummaryOfBasicAndDilutedLossPerShareDetails</Role>
      <ShortName>Net Loss per Share - Summary of Basic and Diluted Loss Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>996015 - Disclosure - Net Loss per Share - Schedule of Diluted Net Loss Per Share Attributable to Common Stockholders Anti-Diluted Effect (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureNetLossPerShareScheduleOfDilutedNetLossPerShareAttributableToCommonStockholdersAntiDilutedEffectDetails</Role>
      <ShortName>Net Loss per Share - Schedule of Diluted Net Loss Per Share Attributable to Common Stockholders Anti-Diluted Effect (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>996025 - Disclosure - Segment Reporting (Additional Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReportingAdditionalInformationDetails</Role>
      <ShortName>Segment Reporting (Additional Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReportingTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>996035 - Disclosure - Segment Reporting - Schedule of Segment Reporting Presents Reportable Segment Profit and Loss (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReportingScheduleOfSegmentReportingPresentsReportableSegmentProfitAndLossDetails</Role>
      <ShortName>Segment Reporting - Schedule of Segment Reporting Presents Reportable Segment Profit and Loss (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>996045 - Disclosure - Segment Reporting - Schedule of Segment Reporting Presents Reportable Segment Profit and Loss (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/DisclosureSegmentReportingScheduleOfSegmentReportingPresentsReportableSegmentProfitAndLossParentheticalDetails</Role>
      <ShortName>Segment Reporting - Schedule of Segment Reporting Presents Reportable Segment Profit and Loss (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="kymr-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>996055 - Disclosure - Subsequent Events - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.kymeratx.com/20260331/taxonomy/role/Role_DisclosureSubsequentEventsAdditionalInformationDetails</Role>
      <ShortName>Subsequent Events - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</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="kymr-20260331.htm">kymr-20260331.htm</File>
    <File>kymr-20260331.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="562">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="19">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
