Options pending award offshore wind contracts.

No definition available.

Name:	gldd_OptionsPendingAwardOffshoreWindContracts
Namespace Prefix:	gldd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of performance obligation to be recognized as revenue.

+ References

No definition available.

+ Details

Name:	gldd_PercentageOfPerformanceObligationToBeRecognizedAsRevenue
Namespace Prefix:	gldd_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Performance obligation expected to be recognized as revenue, year.

+ References

No definition available.

+ Details

Name:	gldd_PerformanceObligationExpectedToBeRecognizedAsRevenueYear
Namespace Prefix:	gldd_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Performance obligations domestic low bids pending formal award and additional phases.

+ References

No definition available.

+ Details

Name:	gldd_PerformanceObligationsDomesticLowBidsPendingFormalAwardAndAdditionalPhases
Namespace Prefix:	gldd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Performance obligations exclude from dredging backlog.

+ References

No definition available.

+ Details

Name:	gldd_PerformanceObligationsExcludeFromDredgingBacklog
Namespace Prefix:	gldd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 340
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479483/340-40-50-3

+ Details

Name:	us-gaap_CapitalizedContractCostAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 340
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479483/340-40-50-3

+ Details

Name:	us-gaap_CapitalizedContractCostGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-SubTopic 10
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-13

+ Details

Name:	us-gaap_RevenueRemainingPerformanceObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Year in which remaining performance obligation is expected to be recognized, in YYYY format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-SubTopic 10
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-13

+ Details

Name:	us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionYear1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:gYearListItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherCurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Revenue (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Revenue (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, remaining performance obligation	$ 968.5
Performance obligations exclude from dredging backlog	44.9
Performance obligations domestic low bids pending formal award and additional phases	$ 265.3
Percentage of performance obligation to be recognized as revenue	60.00%
Performance obligation, expected to be recognized as revenue year	2025
Remaining performance obligation, expected timing of satisfaction, year	2025 2026
Amortization on pre-construction costs	$ 3.4	$ 4.4
Options pending award related to offshore wind contracts	14.5
Other Current Assets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Costs to fulfill contract customers recognized as asset	12.3		$ 10.3
Other Noncurrent Assets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Costs to fulfill contract customers recognized as asset	$ 2.7		$ 7.6