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Financial instruments and risk management - Summary of impact of hedging instrument on statement of financial position (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2018 USD ($)
Aluminium embedded derivatives separated from the power contract [Member] |
Disclosure Of Financial Instruments [Line Items] |
Notional amount | $ 1,786
Carrying value | 8
Change in fair value used for measuring ineffectiveness for the period | 205
Aluminium embedded derivatives separated from the power contract [Member] | Othe financial assets [Member] |
Disclosure Of Financial Instruments [Line Items] |
Line item in the statement of financial position | 54
Aluminium embedded derivatives separated from the power contract [Member] | Other financial liability [Member] |
Disclosure Of Financial Instruments [Line Items] |
Line item in the statement of financial position | 46
Highly Probable Forecast Aluminum Sales |
Disclosure Of Financial Instruments [Line Items] |
Change in fair value used for measuring ineffectiveness for the period | (182)
Cash flow hedge reserve US$m | $ 179

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- Definition The gain (loss) on the change in fair value of the hedged item used as a basis for recognising hedge ineffectiveness. Hedge ineffectiveness is the extent to which the changes in the fair value or the cash flows of the hedging instrument are greater or less than those on the hedged item. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24B -Subparagraph a -Clause iv -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_a_iv&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24B -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_b_i&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The gains (losses) on hedging instruments in fair value hedges. [Refer: Fair value hedges [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Expiry date 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_24_a_i&doctype=Standard&book=B -URIDate 2017-03-09 + Details
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- Definition The nominal or face amount of a financial instrument, used to calculate payments made on that instrument. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 112 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition A component of equity representing the reserve of cash flow hedges in relation to continuing hedges. [Refer: Reserve of cash flow hedges] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Note Effective 2018-01-01 -Name IFRS -Number 7 -IssueDate 2017-01-01 -Paragraph 24B -Subparagraph b -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_b_ii&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition Carrying value of hedging instrument. + References No definition available. + Details
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- Definition Hedging instrument included in statement of financial position. + References No definition available. + Details
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- Details
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