Percentage of performance obligation to be recognized as revenue.

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Performance obligation expected to be recognized as revenue, year.

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Performance obligations exclude from dredging backlog.

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

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

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Long-lived assets other than financial instruments, long-term customer relationships of a financial institution, mortgage and other servicing rights, deferred policy acquisition costs, and deferred tax assets.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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

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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.

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Revenue (Narrative) (Details) - USD ($)	12 Months Ended
Revenue (Narrative) (Details) - USD ($)	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Revenues from External Customers and Long-Lived Assets [Line Items]
Performance obligations exclude from dredging backlog	$ 44,900,000
Revenue, remaining performance obligation	$ 1,190,000,000
Percentage of performance obligation to be recognized as revenue	60.00%
Performance obligation, expected to be recognized as revenue year	2025
Amortization on pre-contract and pre-construction costs	$ 21,900,000	$ 11,500,000
Contract revenues	762,693,000	589,625,000	$ 648,781,000
Long-lived assets, net book value		$ 0	$ 0
Dredging [Member] \| Use of Equipment [Member] \| Federal Government [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Contract revenues	$ 27,700,000
Dredging [Member] \| Sales [Member] \| Geographic Concentration Risk [Member] \| Middle East [Member] \| Maximum [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	1.00%	1.00%	1.00%
Dredging [Member] \| Sales [Member] \| Federal Government Agencies [Member] \| Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	57.00%	75.00%	67.00%
Dredging [Member] \| Accounts Receivable [Member] \| Geographic Concentration Risk [Member] \| Middle East [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	0.00%		9.00%
Dredging [Member] \| Accounts Receivable [Member] \| Federal Government Agencies [Member] \| Customer Concentration Risk [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk percentage	19.00%	35.00%
Other Current Assets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Costs to fulfill contracts with customers recognized as an asset	$ 10,300,000	$ 22,200,000
Other Noncurrent Assets [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Costs to fulfill contracts with customers recognized as an asset	$ 7,600,000	$ 4,000,000