Annual report pursuant to Section 13 and 15(d)

Revenue, Contract Assets and Liabilities and Other Contract Matters - Additional Information (Details)

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Revenue, Contract Assets and Liabilities and Other Contract Matters - Additional Information (Details)
 9 Months Ended 12 Months Ended
Sep. 30, 2019
USD ($)
Dec. 31, 2019
USD ($)
vessel
Vechicle
Project
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2020
Long Term Contracts Or Programs Disclosure [Line Items]          
Bad debt expense   $ 59,000 $ 30,000 $ 21,000  
Allowance for bad debt   15,000,000 400,000    
Reduction of estimated contract price for liquidated damages, amount   12,900,000 11,200,000 11,200,000  
Change in estimated margins   17,200,000 9,100,000 $ 34,500,000  
Reversal of gross profit recognized $ 2,500,000 $ 800,000      
Number of research vessels projects | vessel   3      
Contract assets, noncurrent   $ 12,452,000 12,452,000    
Retainage   $ 3,000,000 3,000,000    
Shipyard          
Long Term Contracts Or Programs Disclosure [Line Items]          
Number of projects in a loss position | Project   2      
Harbor tug          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 4,900,000 6,700,000    
Reserve for loss   $ 1,600,000      
Harbor tug | Minimum          
Long Term Contracts Or Programs Disclosure [Line Items]          
Projects, percent complete (percentage)   60.00%      
Harbor tug | Maximum          
Long Term Contracts Or Programs Disclosure [Line Items]          
Projects, percent complete (percentage)   93.00%      
Ice-Breaker Tug          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 1,500,000      
Projects, percent complete (percentage)   91.00%      
Reserve for loss   $ 100,000      
Forty-Vehicle Ferry          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 5,100,000      
Projects, percent complete (percentage)   28.00%      
Reserve for loss   $ 3,000,000      
Number of vehicle ferry projects | Vechicle   2      
Forty-Vehicle Ferry | Scenario Forecast          
Long Term Contracts Or Programs Disclosure [Line Items]          
Projects, percent complete (percentage)         53.00%
Paddle Wheel River Boat          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 1,300,000      
Projects, percent complete (percentage)   88.00%      
Reserve for loss   $ 200,000      
Jack and Deck          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 2,000,000      
Projects, percent complete (percentage)   46.00%      
Reserve for loss   $ 1,100,000      
Subsea Components Project          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins   $ 1,600,000      
Projects, percent complete (percentage)   86.00%      
Reserve for loss   $ 200,000      
Petrochemical Modules Project          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins     $ 2,400,000