Quarterly report pursuant to Section 13 or 15(d)

Revenue Recognition - Narrative (Details)

v3.8.0.1
Revenue Recognition - Narrative (Details) - USD ($)
3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Long-term Contracts or Programs Disclosure [Line Items]    
Contracts in progress $ 37,509,000 $ 28,373,000
Advance billings on contracts 4,301,000 5,136,000
Accrued contract losses 6,320,000 7,618,000
Costs in Excess of Billings | Customer Concentration Risk | Two Major Customers    
Long-term Contracts or Programs Disclosure [Line Items]    
Contracts in progress 27,000,000  
Billings in Excess of Costs | Customer Concentration Risk | Two Major Customers    
Long-term Contracts or Programs Disclosure [Line Items]    
Customer advances 2,800,000  
Shipyard Division    
Long-term Contracts or Programs Disclosure [Line Items]    
Reduction to estimated contract price   $ (11,700,000)
Project, Approved Scope, Unapproved Price    
Long-term Contracts or Programs Disclosure [Line Items]    
Revenue $ 0