Events after the balance sheet date Events after the balance sheet date (Details) $ in Billions	Aug. 05, 2019 USD ($)
August 2019 Share Buy Back Program [Member] \| Major ordinary share transactions
Disclosure of non-adjusting events after reporting period [line items]
Authorized amount for share buy-back program	$ 1.0

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.

No definition available.

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration