Other financial assets - Summary of other financial assets including non-quasi equity loans to equity accounted units (Parenthetical) (Detail) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Disclosure Of Other Assets [Abstract]
Highly liquid financial assets held in managed investment funds classified as held for trading	$ 2,584	$ 2,522

The amount of financial assets at fair value through profit or loss classified as held for trading. A financial asset is classified as held for trading if: (a) it is acquired principally for the purpose of selling it in the near term; (b) on initial recognition it is part of a portfolio of identified financial instruments that are managed together and for which there is evidence of a recent actual pattern of short-term profit-taking; or (c) it is a derivative (except for a derivative that is a financial guarantee contract or a designated and effective hedging instrument). [Refer: At fair value [member]; Financial assets at fair value through profit or loss]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_55&doctype=Standard
-URIDate 2019-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2021-01-01
-Name IFRS
-Number 7
-IssueDate 2019-01-01
-Paragraph 8
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=7&code=ifrs-tx-2017-en-b&anchor=para_8_a&doctype=Standard&book=b
-URIDate 2019-03-27

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