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.

No definition available.

+ Details

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

- Definition

Fair value of all derivative assets designated as fair value hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

+ Details

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

- Definition

Fair value of all derivative liabilities designated as fair value hedging instruments.

+ References

+ Details

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

- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
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- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=gldd_FuelHedgeContractsMember
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- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_AccountsPayableAndAccruedLiabilitiesMember
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Fair Value Measurements (Schedule of Fair Value of Fuel Hedge Contracts Balance Sheet Location) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives Fair Value [Line Items]
Asset derivatives		$ 2,501
Liability derivatives	$ 4,710
Other Current Assets [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Asset derivatives		$ 2,501
Accrued Expenses [Member] \| Derivatives Designated as Hedging Instruments [Member] \| Fuel Hedge Contracts [Member]
Derivatives Fair Value [Line Items]
Liability derivatives	$ 4,710