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v3.25.2

Commitments and Contingencies (Narrative) (Details) | Jun. 30, 2025 USD ($)
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Commitments And Contingencies [Line Items] |
Outstanding performance bonds | $ 1,300,000,000
Revenue value remaining from outstanding performance bonds | 651,900,000
Minimum [Member] |
Commitments And Contingencies [Line Items] |
Bids bond range | 1,000,000
Maximum [Member] |
Commitments And Contingencies [Line Items] |
Bids bond range | $ 10,000,000

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- Definition Bids bond range. + References No definition available. + Details
Name: | gldd_BidsBondRange
Namespace Prefix: | gldd_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Commitments and contingencies. + References No definition available. + Details
Name: | gldd_CommitmentsAndContingenciesLineItems
Namespace Prefix: | gldd_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Outstanding performance bonds. + References No definition available. + Details
Name: | gldd_OutstandingPerformanceBonds
Namespace Prefix: | gldd_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Revenue value remaining from outstanding performance bonds. + References No definition available. + Details
Name: | gldd_RevenueValueRemainingFromOutstandingPerformanceBonds
Namespace Prefix: | gldd_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |