Issued capital - Summary of Issued Capital (Parenthetical) (Detail) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Par value	$ 0.10	$ 0.10

The nominal value per share.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2019-01-01
-Paragraph 79
-Subparagraph a
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2019-en-r&anchor=para_79_a_iii&doctype=Standard
-URIDate 2019-03-27

Name:	ifrs-full_ParValuePerShare
Namespace Prefix:	ifrs-full_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant