Consolidated statement of financial position (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Class A common stock [member]
Common stock, shares issued	33,776,480	33,743,286
Common stock, shares outstanding	31,185,641	31,112,356
Class B common stock [member]
Common stock, shares issued	10,938,125	10,938,125
Common stock, shares outstanding	10,938,125	10,938,125
Common stock, no par value

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 2017-01-01
-Paragraph 79
-Subparagraph a
-Clause iv
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_79_a_iv&doctype=Standard
-URIDate 2017-03-09

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