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Inventory (Narrative) (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Disclosure of inventories [Abstract] |  |
Long-term inventory | $ 68.7 | $ 75.8
Mining and processing costs, inventories | 323.3 | 304.1
Amortization costs, Inventories | $ 125.6 | $ 119.0

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- Definition Amortization Costs, Inventories + References No definition available. + Details
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- Definition Mining and Processing Costs, Inventories + References No definition available. + Details
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- Definition The amount of non-current inventories. [Refer: Inventories] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2017-01-01 -Paragraph 54 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_54_g&doctype=Standard -URIDate 2017-03-09 + Details
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