Share Capital (Equity Financing) (Details) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
Feb. 09, 2017 USD ($) $ / shares shares	Dec. 31, 2017 CAD / shares	Dec. 31, 2016 CAD / shares
Equity Financing [Line Items]
Equity financing (in shares) \| shares	31,450,000
Share price (usd per share) \| (per share)	$ 7.95	CAD 9.40	CAD 8.78
Gross proceeds from equity financing	$ 250.0
Transaction costs, equity financing	10.9
Equity Financing [Member]
Equity Financing [Line Items]
Deferred tax assets	$ 2.7

The amounts of income taxes recoverable in future periods in respect of: (a) deductible temporary differences; (b) the carryforward of unused tax losses; and (c) the carryforward of unused tax credits. [Refer: Temporary differences [member]; Unused tax credits [member]; Unused tax losses [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 12
-IssueDate 2017-01-01
-Paragraph 81
-Subparagraph g
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2017-03-01&anchor=para_81_g_i&doctype=Standard
-URIDate 2017-03-09

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 54
-Subparagraph o
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_o&doctype=Standard
-URIDate 2017-03-09

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 56
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_56&doctype=Standard
-URIDate 2017-03-09

Name:	ifrs-full_DeferredTaxAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant