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Consolidated net debt - Exchange gains/(losses) on US dollar net debt and intragroup balances (Detail) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Net Exchange Gains And Losses [Abstract] |  |  |
Exchange gains/(losses) on US dollar net debt | $ 554 | $ 160 | $ (1,578)
Exchange (losses)/gains on intragroup balances | (1,154) | 449 | (1,961)
Exchange (losses)/gains on settlement of dividends | (1) | 2 | 1
(Charged)/credited to income statement | $ (601) | $ 611 | $ (3,538)

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- Definition Exchange gains loss on settlement of dividends. + References No definition available. + Details
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- Definition Exchange gains/(losses) on intragroup balances. + References No definition available. + Details
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- Definition Exchange gains losses on net debt. + References No definition available. + Details
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Balance Type: | credit
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- Definition Exchange gains on US dollar net debt and intra group + References No definition available. + Details
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Namespace Prefix: | rio_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Net Exchange Gains And Losses [Abstract]. + References No definition available. + Details
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Balance Type: | na
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