Property, plant and equipment - Summary of Net Book Value of Property, Plant and Equipment by Operating Segment (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	$ 153	$ 157	[1]	$ 137
Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	57	61		52
Fixtures, fittings and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	96	$ 96		$ 85
Americas [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	82
Americas [member] | Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	51
Americas [member] | Fixtures, fittings and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	31
EMEAA [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	5
EMEAA [member] | Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	1
EMEAA [member] | Fixtures, fittings and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	4
Greater China [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	0
Greater China [member] | Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	0
Greater China [member] | Fixtures, fittings and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	0
Central [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	66
Central [member] | Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	5
Central [member] | Fixtures, fittings and equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property plant and equipment	$ 61

[1] Re-presented for the adoption of IFRS 17 ‘Insurance Contracts’ (see New accounting standards and other presentational changes).