Consolidated statement of comprehensive (loss)/income (parenthetical) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of comprehensive income [abstract]
Actuarial (losses)/gains from defined benefit plans, tax expense (benefit)	$ (13,000,000)	$ (11,000,000)	$ 2,000,000
Fair value adjustments on equity securities, tax expense (benefit)	$ (3,000,000)	$ 5,000,000	$ 0

The amount of income tax relating to amounts recognised in other comprehensive income in relation to investments in equity instruments that the entity has designated at fair value through other comprehensive income. [Refer: Other comprehensive income; Reserve of gains and losses from investments in equity instruments]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2020-01-01
-Paragraph 81
-Subparagraph ab
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-URIDate 2020-01-01

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 90
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_90&doctype=Standard
-URIDate 2020-01-01

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