<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>201</ContextCount>
  <ElementCount>371</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>63</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Condensed Consolidated Balance Sheets (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnaudited</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfOperationsAndComprehensiveLossUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityDeficitUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Statement - Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquityDeficitUnauditedParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Unaudited) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows (Unaudited)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - General</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureGeneral</Role>
      <ShortName>General</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - Cash, Cash Equivalents and Restricted Cash</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureCashCashEquivalentsAndRestrictedCash</Role>
      <ShortName>Cash, Cash Equivalents and Restricted Cash</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureInventories</Role>
      <ShortName>Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Prepaid Expenses and Other Current Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssets</Role>
      <ShortName>Prepaid Expenses and Other Current Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Property, Plant, and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipment</Role>
      <ShortName>Property, Plant, and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureAccruedExpenses</Role>
      <ShortName>Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Outstanding Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureOutstandingDebt</Role>
      <ShortName>Outstanding Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Stockholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquity</Role>
      <ShortName>Stockholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Net Loss per Common Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShare</Role>
      <ShortName>Net Loss per Common Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureTaxes</Role>
      <ShortName>Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - General (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureGeneralPolicies</Role>
      <ShortName>General (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Cash, Cash Equivalents and Restricted Cash (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureCashCashEquivalentsAndRestrictedCashTables</Role>
      <ShortName>Cash, Cash Equivalents and Restricted Cash (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureCashCashEquivalentsAndRestrictedCash</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureInventoriesTables</Role>
      <ShortName>Inventories (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureInventories</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Prepaid Expenses and Other Current Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssetsTables</Role>
      <ShortName>Prepaid Expenses and Other Current Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssets</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Property, Plant, and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipmentTables</Role>
      <ShortName>Property, Plant, and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipment</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureAccruedExpensesTables</Role>
      <ShortName>Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureAccruedExpenses</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeases</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Stockholders' Equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityTables</Role>
      <ShortName>Stockholders' Equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquity</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurements</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Net Loss per Common Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareTables</Role>
      <ShortName>Net Loss per Common Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShare</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - General - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureGeneralAdditionalInformationDetails</Role>
      <ShortName>General - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Cash, Cash Equivalents and Restricted Cash - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureCashCashEquivalentsAndRestrictedCashScheduleOfCashCashEquivalentsAndRestrictedCashDetails</Role>
      <ShortName>Cash, Cash Equivalents and Restricted Cash - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Inventories - Schedule of Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureInventoriesScheduleOfInventoriesDetails</Role>
      <ShortName>Inventories - Schedule of Inventories (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssetsScheduleOfPrepaidExpensesAndOtherCurrentAssetsDetails</Role>
      <ShortName>Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePrepaidExpensesAndOtherCurrentAssetsScheduleOfPrepaidExpensesAndOtherCurrentAssetsDetailsParenthetical</Role>
      <ShortName>Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) (Parenthetical)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Property, Plant, and Equipment - Components of Property, Plant, and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipmentComponentsOfPropertyPlantAndEquipmentDetails</Role>
      <ShortName>Property, Plant, and Equipment - Components of Property, Plant, and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Property, Plant, and Equipment - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosurePropertyPlantAndEquipmentAdditionalInformationDetails</Role>
      <ShortName>Property, Plant, and Equipment - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Accrued Expenses - Schedule of Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureAccruedExpensesScheduleOfAccruedExpensesDetails</Role>
      <ShortName>Accrued Expenses - Schedule of Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Accrued Expenses - Schedule of Accrued Expenses (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureAccruedExpensesScheduleOfAccruedExpensesParentheticalDetails</Role>
      <ShortName>Accrued Expenses - Schedule of Accrued Expenses (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Leases - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeasesAdditionalInformationDetails</Role>
      <ShortName>Leases - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Leases - Summary of Operating and Financing Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeasesSummaryOfOperatingAndFinancingLeasesDetails</Role>
      <ShortName>Leases - Summary of Operating and Financing Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Leases - Schedule of Remaining Maturity of Operating Leases Excluding Short-Term Leases (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureLeasesScheduleOfRemainingMaturityOfOperatingLeasesExcludingShortTermLeasesDetails</Role>
      <ShortName>Leases - Schedule of Remaining Maturity of Operating Leases Excluding Short-Term Leases (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Outstanding Debt - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureOutstandingDebtAdditionalInformationDetails</Role>
      <ShortName>Outstanding Debt - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Stockholders' Equity - Preferred Stock Issuances - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityPreferredStockIssuancesAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity - Preferred Stock Issuances - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Stockholders' Equity - Common Stock Issuances - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityCommonStockIssuancesAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity - Common Stock Issuances - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Stockholders' Equity - At-the-Market Offering - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityAtMarketOfferingAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity - At-the-Market Offering - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Stockholders' Equity - Equity Incentive Plan - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityEquityIncentivePlanAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity - Equity Incentive Plan - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Stockholders' Equity - Share-Based Compensation - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquityShareBasedCompensationAdditionalInformationDetails</Role>
      <ShortName>Stockholders' Equity - Share-Based Compensation - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Stockholders' Equity - Summary of Stock Option Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquitySummaryOfStockOptionActivityDetails</Role>
      <ShortName>Stockholders' Equity - Summary of Stock Option Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Stockholders' Equity - Summary of Recognized Share-based Compensation Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquitySummaryOfRecognizedShareBasedCompensationCostDetails</Role>
      <ShortName>Stockholders' Equity - Summary of Recognized Share-based Compensation Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100530 - Disclosure - Stockholders' Equity - Summary of Warrant Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureStockholdersEquitySummaryOfWarrantActivityDetails</Role>
      <ShortName>Stockholders' Equity - Summary of Warrant Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100540 - Disclosure - Fair Value Measurements - Fair Value Measurements Using Significant Unobservable Inputs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurementsFairValueMeasurementsUsingSignificantUnobservableInputsDetails</Role>
      <ShortName>Fair Value Measurements - Fair Value Measurements Using Significant Unobservable Inputs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Fair Value Measurements - Schedule of Fair Value of Outstanding Warrants (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurementsScheduleOfFairValueOfOutstandingWarrantsDetails</Role>
      <ShortName>Fair Value Measurements - Schedule of Fair Value of Outstanding Warrants (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureFairValueMeasurementsAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100570 - Disclosure - Net Loss per Common Share - Anti-Dilutive Securities Excluded from Computation of Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareAntiDilutiveSecuritiesExcludedFromComputationOfEarningsPerShareDetails</Role>
      <ShortName>Net Loss per Common Share - Anti-Dilutive Securities Excluded from Computation of Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Net Loss per Common Share - Calculation of Net Loss and Number of Shares Used to Compute Basic and Diluted Earnings per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareCalculationOfNetLossAndNumberOfSharesUsedToComputeBasicAndDilutedEarningsPerShareDetails</Role>
      <ShortName>Net Loss per Common Share - Calculation of Net Loss and Number of Shares Used to Compute Basic and Diluted Earnings per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Net Loss per Common Share - Calculation of Net Loss and Number of Shares Used to Compute Basic and Diluted Earnings per Share (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareCalculationOfNetLossAndNumberOfSharesUsedToComputeBasicAndDilutedEarningsPerShareParentheticalDetails</Role>
      <ShortName>Net Loss per Common Share - Calculation of Net Loss and Number of Shares Used to Compute Basic and Diluted Earnings per Share (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Net Loss per Common Share - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareAdditionalInformationDetails</Role>
      <ShortName>Net Loss per Common Share - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Net Loss per Common Share - Summary of Reconciliation of Weighted Average Shares Outstanding Calculation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureNetLossPerCommonShareSummaryOfReconciliationOfWeightedAverageSharesOutstandingCalculationDetails</Role>
      <ShortName>Net Loss per Common Share - Summary of Reconciliation of Weighted Average Shares Outstanding Calculation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Taxes - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureTaxesAdditionalInformationDetails</Role>
      <ShortName>Taxes - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Commitments and Contingencies - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureCommitmentsAndContingenciesAdditionalInformationDetails</Role>
      <ShortName>Commitments and Contingencies - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="dcth-20200930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>100640 - Disclosure - Subsequent Events - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.delcath.com/20200930/taxonomy/role/DisclosureSubsequentEventsAdditionalInformationDetails</Role>
      <ShortName>Subsequent Events - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>dcth-20200930.xml</File>
    <File>dcth-20200930.xsd</File>
    <File>dcth-20200930_cal.xml</File>
    <File>dcth-20200930_def.xml</File>
    <File>dcth-20200930_lab.xml</File>
    <File>dcth-20200930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/us-gaap/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2020-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2020-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
