Quarterly report pursuant to Section 13 or 15(d)

Contracts Receivable and Retainage - Additional Information (Detail)

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Contracts Receivable and Retainage - Additional Information (Detail)
 3 Months Ended 6 Months Ended
Mar. 31, 2015
USD ($)
Jun. 30, 2015
USD ($)
Customer
Project
Jun. 30, 2014
USD ($)
Dec. 31, 2014
USD ($)
Long-term Contracts or Programs Disclosure [Line Items]        
Contract receivable   $ 37,402,000   $ 80,448,000
Number of projects per customer | Project   2    
Number of inland river towing vessel projects | Project   3    
Allowance for bad debt   $ 0    
Bad debt expense   400,000 $ 0  
Large Deepwater Customer        
Long-term Contracts or Programs Disclosure [Line Items]        
Receivables, long-term contracts or programs       $ 10,000,000
Cash settlement with customer $ 8,400,000      
Contract equipment transferred to property plant and equipment   $ 1,200,000    
Contract equipment, useful life   15 years    
Bad debt expense   $ 400,000    
Top 4 Customer        
Long-term Contracts or Programs Disclosure [Line Items]        
Contract receivable   $ 23,400,000    
Percentage of contract receivable   62.60%    
Number of major customers account for 65.3% of contract receivable | Customer   5