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PROPERTY, PLANT AND EQUIPMENT - Additional Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Utilities    
Disclosure of detailed information about property, plant and equipment [line items]    
Property, plant and equipment, revalued assets, at cost $ 2,961 $ 2,512
Transport    
Disclosure of detailed information about property, plant and equipment [line items]    
Property, plant and equipment, revalued assets, at cost 1,970 1,845
Energy    
Disclosure of detailed information about property, plant and equipment [line items]    
Property, plant and equipment, revalued assets, at cost 2,246 2,122
Accumulated fair value adjustments    
Disclosure of detailed information about property, plant and equipment [line items]    
Gain from revaluation 418 335
Accumulated fair value adjustments | Utilities    
Disclosure of detailed information about property, plant and equipment [line items]    
Gain from revaluation 137 185
Accumulated fair value adjustments | Transport    
Disclosure of detailed information about property, plant and equipment [line items]    
Gain from revaluation 24 25
Accumulated fair value adjustments | Energy    
Disclosure of detailed information about property, plant and equipment [line items]    
Gain from revaluation $ 257 $ 125