Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement Of Changes In Equity [Abstract]
Dividends declared and paid, per share	$ 5.72	$ 4.07	$ 3.32
Capital distribution, per share	$ 3.33	$ 3.33	$ 2.68

The amount, per share, of dividends recognised as distributions to owners.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2016-01-13
-Paragraph 107
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2016-03-30&anchor=para_107&doctype=Standard
-URIDate 2016-03-31

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