Average Realized Price Per Ounce

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Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Impact On Other Comprehensive Income

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Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Impact On Pre-Tax Earnings

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Sensitivity Analysis For Types Of Market Risk, Reasonably Possible Change In Risk Variable, Percent

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Unrealized Gain (Loss) on Derivatives1

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Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

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The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Financial Instruments and Risk Management (Market Price Risk) (Details) $ in Millions	1 Months Ended	12 Months Ended
	Aug. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) $ / oz
Disclosure of detailed information about hedged items [line items]
Financial assets, at fair value			$ 0.4
Gains (losses) on change in fair value of derivatives	$ 0.1
Unrealized gains		$ 0.4	0.3
Market risk [member]
Disclosure of detailed information about hedged items [line items]
Potential percentage change in value		1000.00%
Impact on other comprehensive income		$ 0.8	3.5
Gold Options [Member] \| Market risk [member]
Disclosure of detailed information about hedged items [line items]
Potential percentage change in value		10.00%
Impact on pre-tax earnings		$ 63.0	$ 54.3
Bottom of range [member] \| Gold Options [Member] \| Market risk [member]
Disclosure of detailed information about hedged items [line items]
Average realized price per ounce \| $ / oz			1,146
Top of range [member] \| Gold Options [Member] \| Market risk [member]
Disclosure of detailed information about hedged items [line items]
Average realized price per ounce \| $ / oz			1,349