Investments - Summary of Investments - Asanko preference shares (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Disclosure of detailed information about financial instruments [abstract]
Fair value at beginning of the year	$ 60.3	$ 94.5
Net change in fair value (recognised in OCI)	(39.4)	34.2
Fair value at end of the year	$ 99.7	$ 60.3
Nominal discount rate	19.90%	16.70%

The gains (losses) recognised in other comprehensive income on financial assets measured at fair value through other comprehensive income applying paragraph 4.1.2A of IFRS 9, before tax, before reclassification adjustments. [Refer: Financial assets measured at fair value through other comprehensive income; Other comprehensive income]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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-Subparagraph b
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-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2023-01-01
-Paragraph 20
-Subparagraph a
-Clause viii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2023-en-r&anchor=para_20_a_viii&doctype=Standard
-URIDate 2023-03-23

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