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Segment Information - Summary of Major Customers (Detail) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]
6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Revenue, Major Customer [Line Items]    
Customers with contract revenue 10.00%  
Petroleo Brasileiro Sa [Member]    
Revenue, Major Customer [Line Items]    
Customers with contract revenue 27.00% 17.00%
SA Group [Member]    
Revenue, Major Customer [Line Items]    
Customers with contract revenue 20.00% 22.00%
Saudi Aramco [Member]    
Revenue, Major Customer [Line Items]    
Customers with contract revenue 12.00% 8.00%
Exxon Mobil Corporation [Member]    
Revenue, Major Customer [Line Items]    
Customers with contract revenue 11.00% 7.00%
L L O G [Member]    
Revenue, Major Customer [Line Items]    
Customers with contract revenue 5.00% 18.00%