Earnings (loss) per share attributable to common shareholders (Narrative) (Details)	12 Months Ended
Dec. 31, 2017
Statements [Line Items]
Description of instruments with potential future dilutive effect not included in calculation of diluted earnings per share	Excluded from the calculation of diluted weighted average shares outstanding were 3,613,000 share-based options and 4,000,000 warrants, respectively, that were determined to be anti-dilutive.

The description of instruments (including contingently issuable shares) that could potentially dilute basic earnings per share in the future, but were not included in the calculation of diluted earnings per share because they are antidilutive for the period(s) presented.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 33
-IssueDate 2018-01-01
-Paragraph 70
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=33&date=2018-03-01&anchor=para_70_c&doctype=Standard
-URIDate 2018-03-16

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