Acquisition of Asanko Gold - Summary of Key Assumptions Used to Determine Fair Value of Redeemable Preference Shares at Acquisition (Detail) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($)
Disclosure of detailed information about business combination [abstract]
Par value of the preference shares	$ 165.0
Market-related interest rate	7.85%
Expected redemption period - 2020 to 2023	5 years

The fair value, at acquisition date, of the consideration transferred in a business combination. [Refer: Business combinations [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 3
-IssueDate 2020-01-01
-Paragraph B64
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=3&code=ifrs-tx-2020-en-r&anchor=para_B64_f&doctype=Appendix&subtype=B
-URIDate 2020-01-01

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant