XML 54 R44.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial Instruments - Credit Risks (Details) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Concentration Risk [Line Items]    
Allowance for doubtful accounts receivable, period increase (decrease) $ 3,200 $ 9,200
Credit Concentration Risk    
Concentration Risk [Line Items]    
Maximum exposure 979,738 1,002,410
Carrying Value | Cash and cash equivalents    
Concentration Risk [Line Items]    
Maximum exposure 483,874 414,111
Carrying Value | Trade receivables, net of allowances    
Concentration Risk [Line Items]    
Maximum exposure 395,707 484,101
Carrying Value | Other taxes    
Concentration Risk [Line Items]    
Maximum exposure 52,557 58,346
Carrying Value | Other current assets    
Concentration Risk [Line Items]    
Maximum exposure 26,463 26,327
Carrying Value | Non-current financial assets    
Concentration Risk [Line Items]    
Maximum exposure $ 21,137 $ 19,525