| Revenue, Contract Assets and Liabilities and Other Contract Matters - Summary of Remaining Performance Obligation by Operating Segment (Details) $ in Thousands | Dec. 31, 2020  USD ($) | 
|---|---|
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
| Remaining performance obligation | $ 371,562 | 
| Operating Segments | |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
| Remaining performance obligation | 371,562 | 
| Shipyard | Operating Segments | |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
| Remaining performance obligation | 352,181 | 
| F&S | Operating Segments | |
| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] | |
| Remaining performance obligation | $ 19,381 | 
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