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Dividends - Summary of dividends paid (Detail) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disclosure of Dividends [Line Items]      
Dividends paid during the year $ 5,356 $ 4,250 $ 2,725
Dividends per share: paid during the year $ 3.07 $ 2.35 $ 1.525
Final Dividends [Member]      
Disclosure of Dividends [Line Items]      
Dividends per share: proposed in the announcement of the results for the year 1.80 $ 1.80 $ 1.25
Special Dividends [Member]      
Disclosure of Dividends [Line Items]      
Dividends per share: proposed in the announcement of the results for the year $ 2.43    
Rio Tinto plc [member]      
Disclosure of Dividends [Line Items]      
Previous year final dividend paid $ 2,446 $ 1,725 $ 1,443
Interim dividend paid 1,666 1,530 604
Rio Tinto Limited [member]      
Disclosure of Dividends [Line Items]      
Previous year final dividend paid 731 523 473
Interim dividend paid $ 513 $ 472 $ 205