<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.3</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>220</ContextCount>
  <ElementCount>247</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>60</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>9</UnitCount>
  <MyReports>
    <Report instance="gldd-20250930.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.gldd.com/20250930/taxonomy/role/Role_DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="gldd-20250930.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.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="gldd-20250930.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.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="gldd-20250930.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.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedStatementsOfOperations</Role>
      <ShortName>Condensed Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>75040 - Statement - Condensed Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncome1</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>75050 - Statement - Condensed Consolidated Statements of Comprehensive Income (Loss) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedStatementsOfComprehensiveIncomeLossParenthetical</Role>
      <ShortName>Condensed Consolidated Statements of Comprehensive Income (Loss) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>75060 - Statement - Condensed Consolidated Statements of Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedStatementsOfEquity</Role>
      <ShortName>Condensed Consolidated Statements of Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>75070 - Statement - Condensed Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.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>9</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.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>10</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>995455 - Disclosure - Basis of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureBasisOfPresentation</Role>
      <ShortName>Basis of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>995465 - Disclosure - Earnings per share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShare1</Role>
      <ShortName>Earnings per share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>995475 - Disclosure - Property and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosurePropertyAndEquipment</Role>
      <ShortName>Property and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>995485 - Disclosure - Accrued Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureAccruedExpenses</Role>
      <ShortName>Accrued Expenses</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>995495 - Disclosure - Long-Term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureLongtermDebt</Role>
      <ShortName>Long-Term Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>995505 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>995515 - Disclosure - Share-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureShareBasedCompensation</Role>
      <ShortName>Share-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>995525 - Disclosure - Revenue</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenue</Role>
      <ShortName>Revenue</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>995535 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>995545 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>995555 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSubsequentEvents2</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>995565 - Disclosure - Earnings per share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShareTables</Role>
      <ShortName>Earnings per share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShare1</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>995575 - Disclosure - Property and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosurePropertyAndEquipmentTables</Role>
      <ShortName>Property and Equipment (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosurePropertyAndEquipment</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>995585 - Disclosure - Accrued Expenses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureAccruedExpensesTables</Role>
      <ShortName>Accrued Expenses (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureAccruedExpenses</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>995595 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurements</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>995605 - Disclosure - Revenue (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</Role>
      <ShortName>Revenue (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenue</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>995615 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformation</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>995625 - Disclosure - Basis of Presentation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureBasisOfPresentationNarrativeDetails</Role>
      <ShortName>Basis of Presentation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureBasisOfPresentation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>995635 - Disclosure - Earnings per share - (Computations for Basic and Diluted Earnings Per Share) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShareComputationsForBasicAndDilutedEarningsPerShareDetails</Role>
      <ShortName>Earnings per share - (Computations for Basic and Diluted Earnings Per Share) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShareTables</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>995645 - Disclosure - Earnings per share - (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShareNarrativeDetails</Role>
      <ShortName>Earnings per share - (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureEarningsPerShareTables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>995655 - Disclosure - Property and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosurePropertyAndEquipmentDetails</Role>
      <ShortName>Property and Equipment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosurePropertyAndEquipmentTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>995665 - Disclosure - Accrued Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureAccruedExpensesDetails</Role>
      <ShortName>Accrued Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureAccruedExpensesTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>995675 - Disclosure - Long-Term Debt (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureLongTermDebtNarrativeDetails</Role>
      <ShortName>Long-Term Debt (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureLongtermDebt</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>995685 - Disclosure - Fair Value Measurements (Schedule of Fair Values of Financial Instruments and Nonfinancial Assets and Liabilities Measured at the Reporting Date) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsScheduleOfFairValuesOfFinancialInstrumentsAndNonfinancialAssetsAndLiabilitiesMeasuredAtReportingDateDetails</Role>
      <ShortName>Fair Value Measurements (Schedule of Fair Values of Financial Instruments and Nonfinancial Assets and Liabilities Measured at the Reporting Date) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>995695 - Disclosure - Fair Value Measurements (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsNarrativeDetails</Role>
      <ShortName>Fair Value Measurements (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>995705 - Disclosure - Fair Value Measurements (Changes in Components of Accumulated Other Comprehensive Income (Loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsChangesInComponentsOfAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Fair Value Measurements (Changes in Components of Accumulated Other Comprehensive Income (Loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995715 - Disclosure - Fair Value Measurements (Adjustments Reclassified from Accumulated Balances Other Comprehensive Income (Loss) to Earnings) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsAdjustmentsReclassifiedFromAccumulatedBalancesOtherComprehensiveIncomeLossToEarningsDetails</Role>
      <ShortName>Fair Value Measurements (Adjustments Reclassified from Accumulated Balances Other Comprehensive Income (Loss) to Earnings) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureFairValueMeasurementsTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995725 - Disclosure - Share-Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureShareBasedCompensationNarrativeDetails</Role>
      <ShortName>Share-Based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureShareBasedCompensation</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>995735 - Disclosure - Revenue (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueNarrativeDetails</Role>
      <ShortName>Revenue (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>995745 - Disclosure - Revenue (Summary of Type of Work, Contract Revenues) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueSummaryOfTypeOfWorkContractRevenuesDetails</Role>
      <ShortName>Revenue (Summary of Type of Work, Contract Revenues) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>995755 - Disclosure - Revenue (Summary of Type of Customer, Contract Revenues) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueSummaryOfTypeOfCustomerContractRevenuesDetails</Role>
      <ShortName>Revenue (Summary of Type of Customer, Contract Revenues) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995765 - Disclosure - Revenue (Schedule of Accounts Receivable) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueScheduleOfAccountsReceivableDetails</Role>
      <ShortName>Revenue (Schedule of Accounts Receivable) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>995775 - Disclosure - Revenue (Components of Contracts in Progress) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueComponentsOfContractsInProgressDetails</Role>
      <ShortName>Revenue (Components of Contracts in Progress) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureRevenueTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>995795 - Disclosure - Commitments and Contingencies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesNarrativeDetails</Role>
      <ShortName>Commitments and Contingencies (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>995805 - Disclosure - Segment Information (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformationNarrativeDetails</Role>
      <ShortName>Segment Information (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformationTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>995815 - Disclosure - Segment Information - Summary of Net Income from Company's Reportable Segment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSegmentInformationSummaryOfNetIncomeFromCompanysReportableSegmentDetails</Role>
      <ShortName>Segment Information - Summary of Net Income from Company's Reportable Segment (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="gldd-20250930.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>995825 - Disclosure - Subsequent Events (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.gldd.com/20250930/taxonomy/role/DisclosureSubsequentEventsNarrativeDetails</Role>
      <ShortName>Subsequent Events (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.gldd.com/20250930/taxonomy/role/DisclosureSubsequentEvents2</ParentRole>
      <Position>47</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="gldd-20250930.htm">gldd-20250930.htm</File>
    <File>gldd-20250930.xsd</File>
  </InputFiles>
  <SupplementalFiles>
    <File>img154182479_0.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="1">http://fasb.org/srt/2025</BaseTaxonomy>
    <BaseTaxonomy items="608">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="8">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>false</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
