XML 73 R56.htm IDEA: XBRL DOCUMENT v3.10.0.1
Fair Value of Financial Instruments and Concentrations of Credit Risk - Textual (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Jan. 01, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Other receivables, value added taxes $ 6,300 $ 10,800    
Receivables, net $ 254,394 $ 265,866   $ 257,425
Customer concentration risk [Member] | Revenues [Member] | Twenty largest customers [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Concentration risk, percentage 44.00% 45.00% 53.00%  
Customer concentration risk [Member] | Revenues [Member] | Sonatrach [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Concentration risk, percentage     14.00%  
Difference between revenue guidance in effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Receivables, net $ (8,441)      
Senior notes [Member] | Convertible Notes due 2021 [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Long-term debt, fair value $ 120,900 $ 127,300