Related party disclosures - Summary of Related Party Disclosures for Associates and Joint Ventures (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of transactions between related parties [Line Items]
Revenue from associates and joint ventures	$ 10	$ 10	$ 9
Other amounts owed by associates and joint ventures	3	1	2
Amounts owed to associates and joint ventures	(4)	(2)
Associates [member]
Disclosure of transactions between related parties [Line Items]
Revenue from associates and joint ventures	10	9	8
Other amounts owed by associates and joint ventures	3	1	2
Amounts owed to associates and joint ventures	$ (4)	(2)
Joint ventures [member]
Disclosure of transactions between related parties [Line Items]
Revenue from associates and joint ventures		$ 1	$ 1

The amounts payable resulting from related party transactions. [Refer: Related parties [member]]

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- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

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- Definition

The amount of revenue arising from the rendering of services in related party transactions. [Refer: Revenue; Related parties [member]]

+ References

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- Definition

The amount of receivables due from related parties. [Refer: Related parties [member]]

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