Ordinary dividends - Additional Information (Detail) - $ / shares	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020
Forecast [Member]
Disclosure of Dividends [line items]
Dividend payable date	Jul. 09, 2021
Interim period amount [member]
Disclosure of Dividends [line items]
Interim dividend per ordinary share	$ 0.125	$ 0.1
Previous period final amount [member]
Disclosure of Dividends [line items]
Final dividend per share		$ 0.14

The amount of dividends paid per ordinary share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 34
-IssueDate 2020-01-01
-Paragraph 16A
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=34&code=ifrs-tx-2020-en-r&anchor=para_16A_f&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_DividendsPaidOrdinarySharesPerShare
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration