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Revenue (Narrative) (Details) - USD ($) | 12 Months Ended
--- | ---
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 |

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