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Share capital - Rio Tinto Limited - Summary of share capital (Detail) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Nov. 30, 2019
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Disclosure of classes of share capital [line items]        
Adjustment on currency translation   $ 205 $ 60  
Rio Tinto Limited        
Disclosure of classes of share capital [line items]        
Number of issued and fully paid up share capital at beginning balance (in shares)   371,210,000 371,210,000 412,410,000
Shares purchased and cancelled (in shares) (41,198,134) 0 0 (41,200,000)
Number of issued and fully paid up share capital at ending balance (in shares)   371,210,000 371,210,000 371,210,000
Issued and fully paid up share capital at beginning balance   $ 3,448 $ 3,477 $ 4,140
Adjustment on currency translation   333 (29) (382)
Ordinary shares purchased and cancelled   0 0 (281)
Issued and fully paid up share capital at ending balance   $ 3,781 $ 3,448 $ 3,477
Rio Tinto Limited | Special voting share        
Disclosure of classes of share capital [line items]        
Other share classes   1 only 1 only 1 only
Rio Tinto Limited | DLC dividend share        
Disclosure of classes of share capital [line items]        
Other share classes   1 only 1 only 1 only