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Goodwill - Additional information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Richards Bay Minerals
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%	8.60%
Pilbara
Disclosure of reconciliation of changes in goodwill [Line Items]
Fair value less costs of disposal, post-tax discount rate	6.60%	6.60%

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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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 2020-01-01
-Paragraph 130
-Subparagraph f
-Clause iii
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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 2020-01-01
-Paragraph B67
-Subparagraph d
-Clause v
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