Deferred tax assets and liabilities (Details 2) - USD ($) $ in Billions	Dec. 31, 2020	Dec. 31, 2019
Investments in subsidiaries [member]
Statement [line items]
Temporary differences on which no deferred tax has been provided as they are permanent in nature	$ 5	$ 3
Goodwill from acquisitions [member]
Statement [line items]
Deductible temporary differences for which no deferred tax liability is recognised	$ (27)	$ (24)

The amount of deductible temporary differences for which no deferred tax asset is recognised in the statement of financial position. [Refer: Temporary differences [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2019-01-01
-Paragraph 81
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=12&code=ifrs-tx-2019-en-r&anchor=para_81_e&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_DeductibleTemporaryDifferencesForWhichNoDeferredTaxAssetIsRecognised
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant