XML 674 R194.htm IDEA: XBRL DOCUMENT v3.20.4
Financial instruments and risk management - Summary of derivative financial instruments (Detail) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items]    
Derivative assets $ 665 $ 366
Derivative financial liabilities (184) (351)
Disclosure Of Information About Amounts Recognised In Balance Sheet [Abstract]    
Non-current assets 531 308
Current assets 134 58
Current liabilities (23) (103)
Non-current liabilities (161) (248)
Total net derivative instruments 481 15
Due within 1 year    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 134 58
Derivative financial liabilities (23) (103)
Between 1 and 5 years    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 330 96
Derivative financial liabilities (14) (86)
More than 5 years    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 201 212
Derivative financial liabilities (147) (162)
Other Financial Assets    
Disclosure of detailed information about financial instruments [line items]    
Total net derivative instruments 481 15
Derivatives designated as hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 461 217
Derivative financial liabilities (160) (322)
Derivatives designated as hedges | Interest rate swaps    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 386 151
Derivative financial liabilities (1) (38)
Derivatives designated as hedges | Cross currency interest rate swaps    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 2 0
Derivative financial liabilities (139) (260)
Derivatives designated as hedges | Aluminium Embedded Derivatives    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 66 66
Derivative financial liabilities (20) (24)
Derivatives designated as hedges | Currency forward contracts    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 7 0
Derivative financial liabilities 0 0
Derivatives not designated as hedges    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 204 149
Derivative financial liabilities (24) (29)
Derivatives not designated as hedges | Aluminium Embedded Derivatives    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 80 96
Derivative financial liabilities 0 0
Derivatives not designated as hedges | Currency forward contracts and swaps    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 63 13
Derivative financial liabilities (1) (5)
Derivatives not designated as hedges | Other embedded derivatives    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 28 14
Derivative financial liabilities (16) 0
Derivatives not designated as hedges | Other commodity contracts    
Disclosure of detailed information about financial instruments [line items]    
Derivative assets 33 26
Derivative financial liabilities $ (7) $ (24)