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Earnings per ordinary share - Summary of earnings (loss) per ordinary shares (Parenthetical) (Detail) - shares shares in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Earnings Per Share [Line Items] |  |  |
Weighted average number of shares outstanding | 1,719.3 | 1,786.7 | 1,797.3
Effect of dilutive securities shares | 12.4 | 12.8 | 11.3
Rio Tinto plc [member] |  |  |
Earnings Per Share [Line Items] |  |  |
Weighted average number of shares outstanding | 1,312.7 | 1,364.5 | 1,373.7
Rio Tinto Limited [member] |  |  |
Earnings Per Share [Line Items] |  |  |
Weighted average number of shares outstanding | 406.6 | 422.3 | 423.6

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- Definition The number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 33 -IssueDate 2017-01-01 -Paragraph 70 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2017-03-01&anchor=para_70_b&doctype=Standard -URIDate 2017-03-09 + Details
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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 The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 33 -IssueDate 2017-01-01 -Paragraph 70 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2017-03-01&anchor=para_70_b&doctype=Standard -URIDate 2017-03-09 + Details
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- Details
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- Details
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