Interest in associates and joint ventures - Carrying amount of interests in associates and joint ventures (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interests In Other Entities [Abstract]
Interests in associates	$ 26,594	$ 24,384
Interests in joint ventures	90	90
Interests in associates and joint ventures	$ 26,684	$ 24,474	$ 22,407

Interests In Other Entities [Abstract]

No definition available.

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- Definition

The amount of investments in associates in an entity's separate financial statements. [Refer: Associates [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 27
-IssueDate 2020-01-01
-Paragraph 10
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=27&code=ifrs-tx-2020-en-r&anchor=para_10&doctype=Standard
-URIDate 2020-01-01

+ Details

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- Definition

The amount of investments in joint ventures in an entity's separate financial statements. [Refer: Joint ventures [member]]

+ References

+ Details

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- Definition

The amount of investments in subsidiaries, joint ventures and associates in an entity's separate financial statements. [Refer: Associates [member]; Joint ventures [member]; Subsidiaries [member]; Investments in subsidiaries]

+ References

+ Details

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