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Exceptional Items - Additional Information (Detail) - USD ($) $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Jun. 30, 2018
Disclosure of exceptional items [line items] |  |  |
Exceptional items net | $ (32) | $ 2,530 | $ 2,970
Samarco dam failure [member] |  |  |
Disclosure of exceptional items [line items] |  |  |
Exceptional items net | $ 210 | $ 210 | $ 650

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- Definition Disclosure of exceptional items. + References No definition available. + Details
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- Definition Exceptional items, net. + References No definition available. + Details
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- Details
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