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Operating segments - Summary of underlying earnings within the reportable segments (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | $ 8,808 | $ 8,627 | $ 5,100
– attributable to owners of Rio Tinto (net earnings) | 13,638 | 8,762 | 4,617
Items excluded from underlying earnings | 4,830 | 135 | (483)
Reportable segments [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | 9,825 | 9,642 | 6,064
Reportable segments [Member] | Iron Ore [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | 6,514 | 6,692 | 4,611
Reportable segments [Member] | Aluminium [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | 1,347 | 1,583 | 947
Reportable segments [Member] | Copper & Diamonds [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | 1,054 | 263 | (18)
Reportable segments [Member] | Energy & Minerals [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | 1,012 | 1,242 | 612
Reportable segments [Member] | Other operations [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
Underlying earnings | (102) | (138) | (88)
Central Pension Costs, Share-Based Payments & Insurance [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | (90) | (48) | (24)
Restructuring, Project and One-Off Costs [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | (190) | (124) | (9)
Exploration and evaluation not attributed to product groups [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | (193) | (178) | (147)
Central Costs [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | (410) | (311) | (208)
Finance costs [Member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | (134) | (354) | (576)
Underlying earnings [member] |  |  |
Disclosure of operating segments [Line Items] |  |  |
– attributable to owners of Rio Tinto (net earnings) | $ 8,808 | $ 8,627 | $ 5,100

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- Definition The profit (loss) attributable to owners of the parent. [Refer: Profit (loss)] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 81B -Subparagraph a -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_81B_a_ii&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition Underlying earnings reflect the following adjustments which are excluded from net earnings/(loss) in each period irrespective of materiality: (1) Net gains/(losses) on disposal and consolidation of interests in businesses. (2) Impairment charges and reversals of cash generating unit. (3) Profit/(loss) after tax from discontinued operations. (4) Certain exchange and derivative gains and losses. This exclusion includes exchange gains/(losses) on US dollar net debt and intragroup balances, gains/(losses) on currency and interest rate derivatives not qualifying for hedge accounting and gains/(losses) on commodity derivatives not qualifying for hedge accounting. + References No definition available. + Details
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