XML 134 R97.htm IDEA: XBRL DOCUMENT v3.8.0.1
Financial risk management - Interest rate risk (Details) - Interest rate risk - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fixed interest rate    
Disclosure of financial instruments by type of interest rate [line items]    
Long-term debt $ 1,188,163 $ 1,186,424
Reasonably possible change in risk variable, percent 1.00%  
Reasonably possible change in risk variable, impact on debt $ 84,000 80,200
Variable interest rate    
Disclosure of financial instruments by type of interest rate [line items]    
Long-term debt $ 314,108 369,782
Reasonably possible change in risk variable, percent 1.00%  
Reasonably possible change in risk variable, impact on pre-tax earnings $ 3,200 3,700
Unsecured notes | Fixed interest rate    
Disclosure of financial instruments by type of interest rate [line items]    
Long-term debt 1,188,163 1,186,424
Egypt limited recourse debt facilities | Variable interest rate    
Disclosure of financial instruments by type of interest rate [line items]    
Long-term debt 241,190 288,515
Other limited recourse debt facilities | Variable interest rate    
Disclosure of financial instruments by type of interest rate [line items]    
Long-term debt $ 72,918 $ 81,267