Line of credit facility optional increase capacity.

No definition available.

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

- Definition

Line of credit facility suppressed capacity.

+ References

No definition available.

+ Details

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

- Definition

Maximum covenant percentage of undrawn availability of amended credit agreement.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Minimum fixed charge coverage ratio per covenant.

+ References

No definition available.

+ Details

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Namespace Prefix:	gldd_
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Balance Type:	na
Period Type:	duration

- Definition

Owned domestic subsidiaries percent.

+ References

No definition available.

+ Details

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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

+ References

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-Topic 210
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+ Details

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

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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

- Details

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Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Balance Type:
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Period Type:

- Details

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- Details

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Namespace Prefix:
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Period Type:

- Details

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Long-Term Debt (Narrative) (Details) - USD ($)		1 Months Ended	3 Months Ended
Long-Term Debt (Narrative) (Details) - USD ($)	Jul. 29, 2022	May 31, 2021	Mar. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Revolving credit facility			$ 50,000,000	$ 0
Minimum fixed charge coverage ratio per covenant	1.10%
Debt instrument covenant description			The springing financial covenant is triggered when the undrawn availability of the Amended Credit Agreement is less than 12.5% of the maximum loan amount for five consecutive days.
Letters of credit outstanding			$ 16,391,000	16,391,000
Letter of credit remaining borrowing capacity			195,712,000	245,713,000
Line of credit facility suppressed capacity			$ 37,897,000	$ 37,897,000
Debt instrument, face amount		$ 325,000,000
2029 Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 325,000,000
Debt instrument, interest rate, stated percentage		5.25%
Maturity date		Jun. 01, 2029
8.000% Senior Notes Due in 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 325,000,000
Debt instrument, interest rate, stated percentage		8.00%
Owned Domestic Subsidiaries Percent		100.00%
Green Loan Advance Rates [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.05%
Minimum [Member] \| Domestic Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.25%
Minimum [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.25%
Maximum [Member] \| Domestic Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.75%
Maximum [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.75%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 300,000,000
Line of credit facility optional increase capacity	$ 100,000,000
Maximum covenant percentage of undrawn availability of amended credit agreement	12.50%
Revolving Credit Facility [Member] \| Domestic Rate [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	0.50%
Revolving Credit Facility [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	1.00%
Green Loan Option [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 35,000,000