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Impairment charges - Summary of impairment charges (Detail) - USD ($)
$ in Millions
 6 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Disclosure of impairment loss recognised or reversed for cash-generating unit [line items]    
Impairment charges   $ 0
Alumina refineries | Aluminium    
Disclosure of impairment loss recognised or reversed for cash-generating unit [line items]    
Impairment charges $ (1,175) 0
Property, plant and equipment    
Disclosure of impairment loss recognised or reversed for cash-generating unit [line items]    
Impairment charges $ (1,175) $ 0