Quarterly report pursuant to Section 13 or 15(d)

REVENUE, CONTRACT ASSETS AND LIABILITIES AND OTHER CONTRACT MATTERS - Narrative (Details)

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REVENUE, CONTRACT ASSETS AND LIABILITIES AND OTHER CONTRACT MATTERS - Narrative (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Dec. 31, 2017
Long-term Contracts or Programs Disclosure [Line Items]            
Bad debt expense $ 0 $ 2,800,000 $ 59,000 $ 2,776,000    
Allowance for bad debt 100,000   100,000   $ 400,000  
Reduction of estimated contract price for liquidated damages, amount 11,800,000   11,800,000   11,200,000 $ 11,200,000
Change in estimated margins 3,900,000   5,800,000      
Retainage 3,000,000   3,000,000   $ 3,000,000  
Harbor Tug            
Long-term Contracts or Programs Disclosure [Line Items]            
Change in estimated margins 1,900,000   3,100,000      
Reserve for loss 1,900,000   1,900,000      
Ice-Breaker Tug            
Long-term Contracts or Programs Disclosure [Line Items]            
Change in estimated margins $ 500,000   $ 1,300,000      
Projects, percent complete (percentage) 85.00%   85.00%      
Reserve for loss $ 100,000   $ 100,000      
Services Project            
Long-term Contracts or Programs Disclosure [Line Items]            
Change in estimated margins $ 1,500,000   $ 1,400,000      
Projects, percent complete (percentage) 56.00%   56.00%      
Reserve for loss $ 600,000   $ 600,000      
Minimum | Harbor Tug            
Long-term Contracts or Programs Disclosure [Line Items]            
Projects, percent complete (percentage) 13.00%   13.00%      
Maximum | Harbor Tug            
Long-term Contracts or Programs Disclosure [Line Items]            
Projects, percent complete (percentage)   88.00%   88.00%