Basis of preparation Disclosure of updates to significant accounting policies (Details) $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
Disclosure of updates to significant accounting policies [Line Items]
Issue of perpetual hybrid bonds	$ 11,861
Non-controlling interests [member] \| Non-controlling interests, hybrid bonds [Member]
Disclosure of updates to significant accounting policies [Line Items]
Issue of perpetual hybrid bonds	$ 11,909

The increase (decrease) in equity resulting from changes that the entity does not separately disclose in the same statement or note. [Refer: Equity]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_106_d&doctype=Standard
-URIDate 2019-03-27

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