Included in Profit/(Loss) Before Royalties and Taxation - Schedule of Amounts Included in Profit/(Loss) Before Royalties and Taxation (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Line items represents amounts included in profit before royalties and taxation [line items]
Restructuring costs	$ 0.6	$ 113.9	$ 9.2
South deep [member]
Line items represents amounts included in profit before royalties and taxation [line items]
Restructuring costs	0.3	11.2	2.3
Damang [member]
Line items represents amounts included in profit before royalties and taxation [line items]
Restructuring costs		13.9	2.2
Tarkwa [member]
Line items represents amounts included in profit before royalties and taxation [line items]
Restructuring costs	$ 0.3	$ 88.8	$ 4.7

The amount of expense relating to restructuring. Restructuring is a programme that is planned and controlled by management and materially changes either the scope of a business undertaken by an entity or the manner in which that business is conducted. Such programmes include: (a) the sale or termination of a line of business; (b) closure of business locations in a country or region or the relocation of activities from one country or region to another; (c) changes in management structure; and (d) fundamental reorganisations that have a material effect on the nature and focus of the entity's operations.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 98
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_98_b&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_ExpenseOfRestructuringActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration