Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
Revenue, Contract Assets and Liabilities and Other Contract Matters - Additional Information (Details)
$ in Millions
 3 Months Ended
Mar. 31, 2020
USD ($)
Vechicle
Mar. 31, 2019
Vechicle
Mar. 31, 2021
Dec. 31, 2019
USD ($)
Dec. 31, 2017
USD ($)
Long Term Contracts Or Programs Disclosure [Line Items]          
Reduction of estimated contract price for liquidated damages, amount $ 11.8     $ 12.9 $ 11.2
Retainage 3.0     $ 3.0  
Forty-Vehicle Ferry          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins $ 1.2        
Number of vehicle ferry projects | Vechicle 2 2      
Projects, percent complete (percentage) 42.00%        
Reserve for loss $ 3.3        
Paddle Wheel Riverboat and Subsea Components Projects          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins 0.9        
Forecast | Forty-Vehicle Ferry          
Long Term Contracts Or Programs Disclosure [Line Items]          
Projects, percent complete (percentage)     55.00%    
Shipyard          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins 1.2        
Fabrication & Services          
Long Term Contracts Or Programs Disclosure [Line Items]          
Change in estimated margins $ 0.9