Related party disclosure (Narrative) (Detail) - Major Defined Benefit Plans [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Related Party Disclosure On Pension And Other Post Employment Benefit Plans [Line Items]
Fees	$ 46	$ 46
Fair value	$ 399	$ 443

The amount of revenue arising from the rendering of services in related party transactions. [Refer: Revenue; Total for all related parties [member]]

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 24
-IssueDate 2024-01-01
-Paragraph 21
-Subparagraph c
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=24&code=ifrs-tx-2024-en-r&anchor=para_21_c&doctype=Standard
-URIDate 2024-03-27

Name:	ifrs-full_RevenueFromRenderingOfServicesRelatedPartyTransactions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration