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Investments in equity accounted units - Additional information (Detail) - USD ($) | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
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Disclosure of Investments in equity accounted units [Line Items] |  |  |
Investments in equity accounted units with shares listed on recognised stock exchanges | $ 0 | $ 0 |
Net debt of the Group | 3,845,000,000 | 9,587,000,000 | $ 13,783,000,000
Investment in equity accounted units [member] |  |  |
Disclosure of Investments in equity accounted units [Line Items] |  |  |
Net debt of the Group | $ 1,244,000,000 | $ 1,338,000,000 |

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- Definition Disclosure of Investments in equity accounted units [Line Items] + References No definition available. + Details
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- Definition Investments Accounted for Using Equity Method, With Shares Listed on Stock Exchanges + References No definition available. + Details
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- Definition The amount of net debt of the entity. + References No definition available. + Details
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- Details
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