Annual report pursuant to Section 13 and 15(d)

SEGMENT INFORMATION, MAJOR CUSTOMERS AND GEOGRAPHICAL DATA Narrative (Details)

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SEGMENT INFORMATION, MAJOR CUSTOMERS AND GEOGRAPHICAL DATA Narrative (Details) - employee
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Brazil      
Revenue, Major Customer [Line Items]      
Number of employees 211    
Sales | Foreign Operations      
Revenue, Major Customer [Line Items]      
Percentage of operating revenues 34.00% 31.00% 21.00%
Sales | Anadarko Petroleum Corporation      
Revenue, Major Customer [Line Items]      
Percentage of operating revenues 28.00% 24.00% 27.00%
Sales | Petroleo Brasileiro S.A.      
Revenue, Major Customer [Line Items]      
Percentage of operating revenues 22.00%    
Sales | U.S. Government      
Revenue, Major Customer [Line Items]      
Percentage of operating revenues 16.00% 16.00% 13.00%
Unionized Employees Concentration Risk | Number of Employees, Total      
Revenue, Major Customer [Line Items]      
Percentage of operating revenues 28.00%