Share capital - Additional information (Details) - shares shares in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disclosure of classes of share capital [abstract]
Number of shares outstanding	680,250	675,957	579,115

The number of shares that have been authorised and issued, reduced by treasury shares held. [Refer: Treasury shares]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 79
-Subparagraph a
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_79_a_iv&doctype=Standard
-URIDate 2020-01-01

Name:	ifrs-full_NumberOfSharesOutstanding
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant