Interest in associates and joint ventures - Carrying amount of interests in associates and joint ventures (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interests In Other Entities [Abstract]
Interests in associates	$ 24,384	$ 22,244
Interests in joint ventures	90	163
Interests in associates and joint ventures	$ 24,474	$ 22,407	$ 22,744

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 2018-01-01
-Paragraph 10
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=27&date=2018-03-01&anchor=para_10&doctype=Standard
-URIDate 2018-03-16

+ 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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