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Share capital - Rio Tinto Limited - Additional Information (Detail) - Rio Tinto Limited [member] - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Value of shares purchased by employee share ownership trusts | $ 37.5 | $ 48.5 | $ 37.0
Shares to held in the employee share ownership trusts on behalf of Rio Tinto Limited | 757,450 |  |

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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
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- Definition Shares in entity held in employee share ownership trust. + References No definition available. + Details
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- Definition Value of shares purchased by employee share ownership trusts. + References No definition available. + Details
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- Details
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