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Financial Instruments and Risk Management (Market Price Risk) (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) $ / oz
Disclosure of detailed information about hedged items [line items] |  |
Unrealized gains | $ 0.4 | $ 0.7
Market risk [member] |  |
Disclosure of detailed information about hedged items [line items] |  |
Potential percentage change in value | 1000.00% |
Impact on other comprehensive income | $ 2.4 | 4.3
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 | $ 81.2 | $ 73.8
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 |  | 1,684
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 |  | 1,943

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