v3.8.0.1
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Foreign Exchange Exposures (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Forward foreign exhange contracts    
Risk management    
Period of time of hedge contracts (in years) 1 year  
Percentage of exposure the hedge covers 100.00%  
Cash flow term (in months) 12 months  
Profit or loss term (in months) 12 months  
Amount contracted $ 2,300 $ 1,800
Currency risk | US Dollar    
Risk management    
Percentage of decrease in risk variable used for sensitivity analysis 10.00%  
Decrease in net borrowings that would result from decreased currency value, per sensitivity analysis $ 3 1
Currency risk | US Dollar | Forward foreign exhange contracts    
Risk management    
Percentage of decrease in risk variable used for sensitivity analysis 10.00%  
Percentage of increase in risk variable used for sensitivity analysis 10.00%  
Increase (decrease) in fair value that would result from decreased currency value, per sensitivity analysis $ (53) (51)
Currency risk | Euro | Forward foreign exhange contracts    
Risk management    
Percentage of decrease in risk variable used for sensitivity analysis 10.00%  
Increase (decrease) in fair value that would result from decreased currency value, per sensitivity analysis $ 12 $ 17