<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>207</ContextCount>
  <ElementCount>296</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>106</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report instance="tmdx-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.transmedics.com/20260331/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>75010 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>75020 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>75030 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperations</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>75040 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>75050 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>75060 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.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>8</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.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>9</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Nature of the Business and Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureNatureOfBusinessAndBasisOfPresentation</Role>
      <ShortName>Nature of the Business and Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Inventory</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureInventory</Role>
      <ShortName>Inventory</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Property, Plant and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosurePropertyPlantAndEquipmentNet</Role>
      <ShortName>Property, Plant and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Goodwill and Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureGoodwillAndIntangibleAssets</Role>
      <ShortName>Goodwill and Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Accrued Expenses and Other Current Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesAndOtherCurrentLiabilities</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Long-term Debt and Financing Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangements1</Role>
      <ShortName>Long-term Debt and Financing Arrangements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureStockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Net Income per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureNetIncomePerShare</Role>
      <ShortName>Net Income per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995545 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Revenue and Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformation</Role>
      <ShortName>Revenue and Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Inventory (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureInventoryTables</Role>
      <ShortName>Inventory (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureInventory</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Property, Plant and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetTables</Role>
      <ShortName>Property, Plant and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/DisclosurePropertyPlantAndEquipmentNet</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Goodwill and Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsTables</Role>
      <ShortName>Goodwill and Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/DisclosureGoodwillAndIntangibleAssets</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Accrued Expenses and Other Current Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesAndOtherCurrentLiabilitiesTables</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesAndOtherCurrentLiabilities</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Long-term Debt and Financing Arrangements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsTables</Role>
      <ShortName>Long-term Debt and Financing Arrangements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangements1</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureStockBasedCompensation</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Net Income per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureNetIncomePerShareTables</Role>
      <ShortName>Net Income per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/DisclosureNetIncomePerShare</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Commitments and Contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and Contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Revenue and Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformationTables</Role>
      <ShortName>Revenue and Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformation</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Nature of the Business and Basis of Presentation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureNatureOfBusinessAndBasisOfPresentationAdditionalInformationDetail</Role>
      <ShortName>Nature of the Business and Basis of Presentation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Summary of Significant Accounting Policies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformationDetail</Role>
      <ShortName>Summary of Significant Accounting Policies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Inventory - Schedule of Inventory, Current (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureInventoryScheduleOfInventoryCurrentDetail</Role>
      <ShortName>Inventory - Schedule of Inventory, Current (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Property, Plant and Equipment, Net - Schedule of Property, Plant and Equipment, Net (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetScheduleOfPropertyPlantAndEquipmentNetDetail</Role>
      <ShortName>Property, Plant and Equipment, Net - Schedule of Property, Plant and Equipment, Net (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Property, Plant and Equipment, Net - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosurePropertyPlantAndEquipmentNetAdditionalInformationDetail</Role>
      <ShortName>Property, Plant and Equipment, Net - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Goodwill and Intangible Assets - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsAdditionalInformationDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureGoodwillAndIntangibleAssetsScheduleOfAcquiredIntangibleAssetsDetail</Role>
      <ShortName>Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureAccruedExpensesAndOtherCurrentLiabilitiesScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesDetail</Role>
      <ShortName>Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Long-Term Debt and Financing Arrangements - Schedule of Notes (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsScheduleOfNotesDetail</Role>
      <ShortName>Long-Term Debt and Financing Arrangements - Schedule of Notes (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Long-Term Debt and Financing Arrangements - Convertible Senior Notes - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsConvertibleSeniorNotesAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt and Financing Arrangements - Convertible Senior Notes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995785 - Disclosure - Long-Term Debt and Financing Arrangements - Capped Call Transactions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsCappedCallTransactionsAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt and Financing Arrangements - Capped Call Transactions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Long-Term Debt and Financing Arrangements - Schedule of Long-term Debt Instruments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsScheduleOfLongtermDebtInstrumentsDetail</Role>
      <ShortName>Long-Term Debt and Financing Arrangements - Schedule of Long-term Debt Instruments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Long-Term Debt and Financing Arrangements - Long-term Debt - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureLongtermDebtAndFinancingArrangementsLongtermDebtAdditionalInformationDetail</Role>
      <ShortName>Long-Term Debt and Financing Arrangements - Long-term Debt - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Stock-Based Compensation - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureStockBasedCompensationAdditionalInformationDetail</Role>
      <ShortName>Stock-Based Compensation - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureStockBasedCompensationScheduleOfStockBasedCompensationExpenseDetail</Role>
      <ShortName>Stock-Based Compensation - Schedule of Stock-Based Compensation Expense (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>995835 - Disclosure - Net Income per Share - Reconciliation of Numerators and Denominators of Basic and Dilutive Net Income per Common Share Computations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureNetIncomePerShareReconciliationOfNumeratorsAndDenominatorsOfBasicAndDilutiveNetIncomePerCommonShareComputationsDetails</Role>
      <ShortName>Net Income per Share - Reconciliation of Numerators and Denominators of Basic and Dilutive Net Income per Common Share Computations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>995845 - Disclosure - Net Income per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureNetIncomePerShareScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareDetails</Role>
      <ShortName>Net Income per Share - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>995855 - Disclosure - Commitments and Contingencies - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesAdditionalInformationDetail</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>995865 - Disclosure - Commitments and Contingencies - Schedule of Components Finance Lease Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureCommitmentsAndContingenciesScheduleOfComponentsFinanceLeaseCostDetails</Role>
      <ShortName>Commitments and Contingencies - Schedule of Components Finance Lease Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>995875 - Disclosure - Commitments and Contingencies - Summary of Future Payments under the Lease (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureCommitmentsAndContingenciesSummaryOfFuturePaymentsUnderTheLeaseDetails</Role>
      <ShortName>Commitments and Contingencies - Summary of Future Payments under the Lease (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>995895 - Disclosure - Revenue and Segment Information - Schedule of Net Revenue by Organ and Country (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformationScheduleOfNetRevenueByOrganAndCountryDetail</Role>
      <ShortName>Revenue and Segment Information - Schedule of Net Revenue by Organ and Country (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>995905 - Disclosure - Revenue and Segment Information - Schedule of Net Revenue by Organ and Country (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformationScheduleOfNetRevenueByOrganAndCountryParentheticalDetail</Role>
      <ShortName>Revenue and Segment Information - Schedule of Net Revenue by Organ and Country (Parenthetical) (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>995915 - Disclosure - Revenue and Segment Information - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformationAdditionalInformationDetail</Role>
      <ShortName>Revenue and Segment Information - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>995925 - Disclosure - Revenue and Segment Information - Summary of Significant Segment Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureRevenueAndSegmentInformationSummaryOfSignificantSegmentExpensesDetail</Role>
      <ShortName>Revenue and Segment Information - Summary of Significant Segment Expenses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>995935 - Disclosure - Related Party Transactions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetail</Role>
      <ShortName>Related Party Transactions - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="tmdx-20260331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>995945 - Disclosure - Income Taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.transmedics.com/20260331/taxonomy/role/DisclosureIncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income Taxes - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</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="tmdx-20260331.htm">tmdx-20260331.htm</File>
    <File>tmdx-20260331.xsd</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="571">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="29">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="7">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
