Quarterly report pursuant to Section 13 or 15(d)

Revenue Recognition - Contracts Receivable and Retainage (Details)

v3.10.0.1
Revenue Recognition - Contracts Receivable and Retainage (Details) - USD ($)
$ in Thousands
3 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]    
Contract receivable $ 28,933 $ 28,466
Allowance for bad debt 3,700  
Increase in allowance for bad debt 2,800  
Contracts in progress 40,187 28,373
Advance billings on contracts 14,930 5,136
Accrued contract losses 6,033 $ 7,618
Contract Receivable | Customer Concentration Risk | One Major Customer    
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]    
Contract receivable 18,400  
Costs in Excess of Billings | Customer Concentration Risk | Three Customers    
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]    
Contracts in progress 37,100  
Billings in Excess of Costs | Customer Concentration Risk | Five Customers    
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]    
Customer advances $ 11,200