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v3.19.3.a.u2

Goodwill - Key assumptions calculation of fair value less costs of disposal (Parenthetical) (Detail) - Richards Bay Minerals [Member] | 12 Months Ended |
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Dec. 31, 2019 | Dec. 31, 2018
Disclosure of key assumptions calculation of fair value less costs of disposal [Line Items] |  |
Fair value less costs of disposal, post-tax discount rate | 8.60% | 8.80%
5% decrease in the titanium slag price | Titanium |  |
Disclosure of key assumptions calculation of fair value less costs of disposal [Line Items] |  |
Percentage of decrease in the titanium slag price | 5.00% |
1% increase in the discount rate applied to post-tax cash flows |  |
Disclosure of key assumptions calculation of fair value less costs of disposal [Line Items] |  |
Fair value less costs of disposal, post-tax discount rate | 1.00% |
10% strengthening of South African rand |  |
Disclosure of key assumptions calculation of fair value less costs of disposal [Line Items] |  |
Strengthening percentage of the South African rand | 10.00% |

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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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