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Revenue (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021 | Dec. 31, 2021
Revenue From Contract With Customer [Line Items] |  |  |  |  |
Revenue, remaining performance obligation | $ 452,587 |  | $ 452,587 |  |
Performance obligations exclude from dredging backlog | $ 50,000 |  | $ 50,000 |  |
Percentage of performance obligation to be recognized as revenue |  |  | 38.00% |  |
Performance obligation, expected to be recognized as revenue year |  |  | 2022 |  |
Remaining performance obligation, expected timing of satisfaction, year | 2023 |  | 2023 |  |
Increased gross profit | $ 4,880 |  | $ 22,242 |  |
Amortization on pre-construction costs | 2,856 | $ 3,687 | 7,308 | $ 15,443 |
Other Current and Noncurrent Assets [Member] |  |  |  |  |
Revenue From Contract With Customer [Line Items] |  |  |  |  |
Costs to fulfill a contract with customer recognized as an asset | $ 5,450 |  | $ 5,450 |  | $ 5,652

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