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Share Capital (Share Capital) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Reconciliation of number of shares outstanding [abstract] |  |
Beginning balance | $ 2,695.3 |
Shares issued through: |  |
Ending balance | $ 2,851.5 | $ 2,695.3
Issued capital [member] |  |
Reconciliation of number of shares outstanding [abstract] |  |
Number of shares outstanding | 391,070,817 | 391,250,203
Beginning balance | $ 3,693.3 | $ 3,705.2
Shares issued through: |  |
Share-based employment compensation plans (in shares) | 1,653,361 | 1,555,989
Share-based compensation plans | $ 10.3 | $ 9.5
Shares repurchased and cancelled (in shares) | (1,133,561) | (2,748,352)
Shares repurchased and cancelled | $ (10.7) | $ (26.1)
Exercise of warrants (in shares) |  | 45
Exercise of warrants |  | $ 0.0
Flow-through share financing (in shares) |  | 1,132,169
Flow-through share financing | 0.0 | $ 5.9
Cancellation of unexchanged post-amalgamation shares |  | (119,237)
Cancellation of unexchanged post-amalgamation shares | $ 0.0 | $ (1.2)
Dividend reinvestment plan and share purchase plan (in shares) | 1,186,205 |
Dividend reinvestment plan and share purchase plan (ii) | $ 10.0 |
Number of shares outstanding | 392,776,822 | 391,070,817
Ending balance | $ 3,702.9 | $ 3,693.3

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