Investment in Associates and Joint Ventures - Summarised Aggregated Financial Information for Individually Immaterial Associates and Joint Ventures (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of investment in associates and joint ventures [line items]
Operating profits before exceptional items	$ (1)	$ 7	$ 7
Joint ventures [member]
Disclosure of investment in associates and joint ventures [line items]
Operating profits before exceptional items	2		5
Associates [member]
Disclosure of investment in associates and joint ventures [line items]
Operating profits before exceptional items	$ (3)	$ 7	$ 2

The entity's share of the profit (loss) from continuing operations of associates and joint ventures accounted for using the equity method. [Refer: Associates [member]; Continuing operations [member]; Investments accounted for using equity method; Joint ventures [member]; Profit (loss) from continuing operations]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2020-01-01
-Paragraph B16
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2020-en-r&anchor=para_B16_a&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:	duration