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Share capital - Rio Tinto plc - Summary of share capital (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Rio Tinto Limited shares were held by Rio Tinto plc | 0 | 0 | 0
Rio Tinto plc [member] |  |  |
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Issued and fully paid up share capital at beginning balance | $ 220,000 | $ 224,000 | $ 224,000
Shares purchased and cancelled | (9,000) | (4,000) |
Issued and fully paid up share capital at ending balance | $ 211,000 | $ 220,000 | $ 224,000
Number of issued and fully paid up share capital at beginning balance | 1,351,609,000 | 1,384,520,000 | 1,384,487,000
Number of shares held by public at beginning balance | 1,351,609,000 | 1,384,520,000 |
Ordinary shares issued | 35,380 | 26,241 | 33,210
Shares purchased and cancelled | $ (63,984) | $ (32,937) |
Shares purchased and cancelled | (63,984,287) | (32,937,109) | 0
Number of issued and fully paid up share capital at ending balance | 1,287,660,000 | 1,351,609,000 | 1,384,520,000
Number of shares held by public at ending balance | 1,287,660,000 | 1,351,609,000 | 1,384,520,000
Rio Tinto plc [member] | Shares held by public [member] |  |  |
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Number of shares held by public at beginning balance | 1,342,058,000 | 1,374,822,000 | 1,374,046,000
Ordinary shares issued | 35,000 | 26,000 | 33,000
Shares reissued from treasury | 106,000 | 147,000 | 743,000
Shares purchased and cancelled | (63,984,000) | (32,937,000) |
Rio Tinto Limited shares were held by Rio Tinto plc | 9,445,000 | 9,551,000 | 9,698,000
Number of shares held by public at ending balance | 1,278,215,000 | 1,342,058,000 | 1,374,822,000
Rio Tinto plc [member] | Special voting share [member] |  |  |
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Other share classes | 1 only | 1 only | 1 only
Rio Tinto plc [member] | DLC dividend share [member] |  |  |
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Other share classes | 1 only | 1 only | 1 only
Rio Tinto plc [member] | Equalisation share [member] |  |  |
Disclosure Of Classes Of Share Capital [Line Items] |  |  |
Other share classes | 1 only | 1 only | 1 only

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