XML 80 R66.htm IDEA: XBRL DOCUMENT
v3.22.4

Retirement Plans (Narrative) (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2022 USD ($) Item | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Defined Contribution Plan Disclosure [Line Items] |  |  |
Number of sponsored 401(k) plans | Item | 2 |  |
Expense for matching and discretionary contributions | $ 2,996 | $ 4,659 | $ 5,557
Contributes to various multiemployer pension plans | $ 4,915 | $ 4,632 | $ 4,929
Maximum [Member] |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Multiemployer plans collective-bargaining arrangement percentage of contributions | 5.00% |  |

X
- Definition Number of sponsored 401(k) plans + References No definition available. + Details
Name: | gldd_NumberOfSponsored401KPlans
Namespace Prefix: | gldd_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cost for defined contribution plan. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
Name: | us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

X
- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage of employer contribution required by collective-bargaining arrangement (CBA) to total contribution from all participating employers in multiemployer pension plan determined to be individually significant. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI https://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
Name: | us-gaap_MultiemployerPlanPensionSignificantEmployerContributionUnderCollectiveBargainingArrangementToAllParticipatingEmployerContributionsPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

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