Earnings Per Share - Weighted Average Ordinary Shares Outstanding Diluted (Details) - shares	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted average ordinary shares and adjusted weighted average ordinary shares [abstract]
Issued shares outstanding at 1 January (in shares)	684,794,839	684,346,294	683,854,491
Effect of RSU shares (in shares)	(396,641)	(23,213)	46,615
Effect of treasury stock (in shares)	320,997	363,083	342,785
Average weighted number of ordinary shares outstanding (diluted) at 31 December (in shares)	684,719,195	684,686,164	684,243,891

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2019-01-01
-Paragraph 70
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=33&code=ifrs-tx-2019-en-r&anchor=para_70_b&doctype=Standard
-URIDate 2019-03-27

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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration