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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, 2018
Nov. 30, 2017
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disclosure of classes of share capital [line items]          
Adjustment on currency translation     $ 9 $ 386  
Rio Tinto Limited [Member]          
Disclosure of classes of share capital [line items]          
Number of issued and fully paid up share capital at beginning balance     371,210,000 412,410,000 424,190,000
Shares purchased and cancelled (41,198,134) (11,778,064) 0 (41,200,000) (11,780,000)
Number of issued and fully paid up share capital at ending balance     371,210,000 371,210,000 412,410,000
Issued and fully paid up share capital at beginning balance     $ 3,477 $ 4,140 $ 3,915
Adjustment on currency translation     (29) (382) 310
Ordinary shares purchased and cancelled     0 (281) (85)
Issued and fully paid up share capital at ending balance     $ 3,448 $ 3,477 $ 4,140
Rio Tinto Limited [Member] | Special voting share [Member]          
Disclosure of classes of share capital [line items]          
Other share classes     1 only 1 only 1 only
Rio Tinto Limited [Member] | DLC dividend share [Member]          
Disclosure of classes of share capital [line items]          
Other share classes     1 only 1 only 1 only