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Goodwill - Additional information (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018
Richards Bay Minerals [Member] |  |
Disclosure of reconciliation of changes in goodwill [Line Items] |  |
Impairment charges | $ 0 | $ 0
Fair value less costs of disposal, post-tax discount rate | 8.60% | 8.80%
Pilbara [Member] |  |
Disclosure of reconciliation of changes in goodwill [Line Items] |  |
Fair value less costs of disposal, post-tax discount rate | 6.60% | 6.80%

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- Definition The discount rate used in the current measurement of fair value less costs of disposal. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 36 -IssueDate 2019-01-01 -Paragraph 130 -Subparagraph f -Clause iii -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=36&code=ifrs-tx-2019-en-r&anchor=para_130_f_iii&doctype=Standard -URIDate 2019-03-27 + Details
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- Definition The amount of impairment loss recognised in profit or loss for goodwill. [Refer: Impairment loss recognised in profit or loss; Goodwill] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 3 -IssueDate 2019-01-01 -Paragraph B67 -Subparagraph d -Clause v -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2019-en-r&anchor=para_B67_d_v&doctype=Appendix&subtype=B -URIDate 2019-03-27 + Details
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