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Principal subsidiaries - Summary of principal in subsidiaries (Parenthetical) (Detail) | 12 Months Ended
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Dec. 31, 2017
Oyu Tolgoi LLC [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Indirect interest in subsidiary | 33.50%
Robe river iron associates [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 65.00%
Non-controlling interest (%), Subsidiary | 12.00%
Proportion of net beneficial interest | 53.00%
Percentage of ownership interest exchanged in joint venture | 65.00%
Hail Creek Joint Venture [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Percentage of ownership interest exchanged in joint venture | 82.00%
Kestrel Joint Venture [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Percentage of ownership interest exchanged in joint venture | 80.00%
Consrcio De Alumnio Do Maranho [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Percentage of ownership interest exchanged in joint venture | 10.00%
Diavik Joint Venture [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Percentage of ownership interest exchanged in joint venture | 60.00%
Robe River Mining Co Pty Ltd [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 60.00%
Non-controlling interest (%), Subsidiary | 40.00%
Robe River Mining Co Pty Ltd [member] | Robe river iron associates [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Non-controlling interest (%), Subsidiary | 30.00%
North Mining Limited [member] | Robe river iron associates [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Non-controlling interest (%), Subsidiary | 35.00%
Simfer Jersey Limited [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 53.00%
Simfer Jersey Limited [member] | Common shares [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 53.00%
Simfer S.A. [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 85.00%
Non-controlling interest (%), Subsidiary | 45.05%
Indirect interest in subsidiary | 45.05%
QIT Madagascar Minerals SA [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 80.00%
Portion of additional economic interest held through non voting investment | 5.00%
Portion of economic interest held through non voting investment | 85.00%
Non-controlling interest voting rights | 20.00%
QIT Madagascar Minerals SA [member] | Common shares [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 80.00%
Proportion of class held (%), Subsidiary | 80.00%
QIT Madagascar Minerals SA [member] | Common Shares and Investment Certificates [Member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Non-controlling interest (%), Subsidiary | 15.00%
Turquoise Hill Resources Ltd [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 50.79%
Turquoise Hill Resources Ltd [member] | Oyu Tolgoi LLC [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 66.00%
Rossing Uranium Limited [member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 68.60%
Proportion of class held (%), Subsidiary | 35.57%
Non-controlling interest voting rights | 64.43%
Richards Bay Mining (Proprietary) Limited [member] | B Ordinary, B Preference and Parent Preference Shares [Member] |
Disclosure Of Significant Investments In Subsidiaries [Line Items] |
Ownership percentage in subsidiary | 74.00%
Non-controlling interest (%), Subsidiary | 26.00%

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