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Share-based payments - Charge has been recognised in income statement for Rio Tinto's share-based incentive plans, and the related liability (for cash-settled plans) (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Charge recognised for the year $ 138 $ 123 $ 122
Liability at the end of the year 7 19  
Equity-settled awards      
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Charge recognised for the year 131 118 118
Liability at the end of the year 0 0  
Cash-settled awards      
Disclosure of terms and conditions of share-based payment arrangement [line items]      
Charge recognised for the year 7 5 $ 4
Liability at the end of the year $ 7 $ 19