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Acquisition of Richmond Mines Ltd. (Schedule of Asset Acquisition) (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | --- | ---
Net assets acquired |  |  |
Cash and cash equivalents | $ 172.5 | $ 220.5 | $ 182.8
Equity securities (note 17) | 23.9 | 43.7 |
Mineral property, plant and equipment | 3,108.5 | 3,101.3 |
Current liabilities | (157.4) | (146.9) |
Deferred tax liability | $ (623.2) | $ (559.9) |

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