Increased gross profit.

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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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Revenue from contract with customer line items.

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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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Revenue (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Revenue (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue From Contract With Customer [Line Items]
Performance obligations exclude from dredging backlog	$ 50,000
Revenue, remaining performance obligation	$ 377,140
Percentage of performance obligation to be recognized as revenue	100.00%
Performance obligation, expected to be recognized as revenue year	2023
Amortization on pre-contract and pre-construction costs	$ 11,148	$ 17,839
Contract revenues	648,781	726,149	$ 733,601
Long-lived assets, net book value	0
Increased gross profit	$ 22,276
Dredging [Member] \| Use of Equipment [Member] \| Federal Government [Member]
Revenue From Contract With Customer [Line Items]
Contract revenues		$ 716
Dredging [Member] \| Sales [Member] \| Geographic Concentration Risk [Member] \| Middle East [Member] \| Maximum [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	10.00%	10.00%	10.00%
Dredging [Member] \| Sales [Member] \| Federal Government Agencies [Member] \| Customer Concentration Risk [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	67.00%	78.00%	80.00%
Dredging [Member] \| Accounts Receivable [Member] \| Geographic Concentration Risk [Member] \| Middle East [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	9.00%	9.00%
Dredging [Member] \| Accounts Receivable [Member] \| Federal Government Agencies [Member] \| Customer Concentration Risk [Member]
Revenue From Contract With Customer [Line Items]
Concentration risk percentage	46.00%	69.00%
Other Current and Noncurrent Assets [Member]
Revenue From Contract With Customer [Line Items]
Costs to fulfill contracts with customers recognized as an asset	$ 4,472	$ 5,652