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Share Capital (Flow-though share financing) (Details) $ / shares in Units, CAD in Millions, $ in Millions | 6 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 $ / shares | Dec. 31, 2017 CAD | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Flow-though Share Financing [Line Items] |  |  |  |
Proceeds from issuance of flow-through shares | $ |  |  | $ 11.7 | $ 20.4
Canadian Development Expense [Member] |  |  |  |
Flow-though Share Financing [Line Items] |  |  |  |
Proceeds from issuance of flow-through shares | CAD |  | CAD 12.0 |  |
Proceeds from flow-through share financing (CAD per share) | $ / shares | $ 10.87 |  |  |
Canadian Exploration Expense [Member] |  |  |  |
Flow-though Share Financing [Line Items] |  |  |  |
Proceeds from issuance of flow-through shares | CAD |  | CAD 3.0 |  |
Proceeds from flow-through share financing (CAD per share) | $ / shares | $ 15.15 |  |  |

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- Definition [Line Items] for Flow-though Share Financing [Table] + References No definition available. + Details
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- Definition Proceeds from Flow-through Share Financing, Per Share + References No definition available. + Details
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- Definition The cash inflow from issuing shares. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 7 -IssueDate 2017-01-01 -Paragraph 17 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2017-03-01&anchor=para_17_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Details
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- Details
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