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v3.19.1

Financial Instruments and Risk Management (Currency Contracts) (Details) $ / shares in Units, $ in Millions, $ in Millions, $ in Millions | 1 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Aug. 31, 2018 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2018 $ / shares | Dec. 31, 2018 CAD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2018 $ / $ | Dec. 31, 2018 $ / $ | Dec. 31, 2018 MXN ($)
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Financial assets, at fair value |  |  | $ 0.4 |  |  |  |  |  |
Financial liabilities, at fair value |  |  |  |  |  | $ 0.1 |  |  |
Gains (losses) on change in fair value of derivatives | $ 0.1 |  |  |  |  |  |  |  |
Collars and Forwards [Member] |  |  |  |  |  |  |  |  |
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Financial assets, at fair value |  |  |  |  |  | $ 4.7 |  |  |
Financial liabilities, at fair value |  |  | 5.0 |  |  |  |  |  |
Gains (losses) on change in fair value of derivatives |  | $ 3.9 | $ (4.3) |  |  |  |  |  |
2019 [member] | Collars [Member] | Currency risk [member] |  |  |  |  |  |  |  |  |
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  |  | $ 342.0 |  |  |  | $ 1,380.0
2019 [member] | Forward contract [member] | Currency risk [member] |  |  |  |  |  |  |  |  |
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Notional amount |  |  |  |  | $ 9.0 |  |  |  |
Forward price (usd per cad) | $ / shares |  |  |  | $ 1.34 |  |  |  |  |
Bottom of range [member] | 2019 [member] | Collars [Member] | Currency risk [member] |  |  |  |  |  |  |  |  |
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Average rate of hedging instrument |  |  |  |  |  |  | 130.00% | 1950.00% |
Top of range [member] | 2019 [member] | Collars [Member] | Currency risk [member] |  |  |  |  |  |  |  |  |
Disclosure of detailed information about hedged items [line items] |  |  |  |  |  |  |  |  |
Average rate of hedging instrument |  |  |  |  |  |  | 135.00% | 2207.00% |

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- Definition The average rate of a hedging instrument. [Refer: Hedging instruments [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 23B -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_23B_b&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The fair value of financial assets. [Refer: At fair value [member]; Financial assets] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 7 -IssueDate 2018-01-01 -Paragraph 25 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard -URIDate 2018-03-16 + Details
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