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Average number of employees - Additional information (Detail) | 12 Months Ended
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Dec. 31, 2018
Number And Average Number Of Employees [Abstract] |
Per cent of employees of subsidiary companies | 100.00%

X
- References No definition available. + Details
Name: | ifrs-full_NumberAndAverageNumberOfEmployeesAbstract
Namespace Prefix: | ifrs-full_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of employees of subsidiary companies. + References No definition available. + Details
Name: | rio_PercentageOfEmployeesOfSubsidiaryCompanies
Namespace Prefix: | rio_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration