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Financial Instruments and Risk Management (Foreign Currency Exchange Rate Risk) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | $ (176.5) | $ (228.1)
Unrealized gains | $ 0.4 | 0.7
Currency risk [member] |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Potential percentage change in value | 10.00% |
Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | $ 574.7 | 458.0
Impact on pre-tax earnings | 1.4 | 3.3
Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | 58.9 | 54.3
Impact on pre-tax earnings | 0.4 | 0.4
Cash and Cash Equivalents [Member] |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk |  | (220.5)
Cash and Cash Equivalents [Member] | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (21.3) | (33.5)
Cash and Cash Equivalents [Member] | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (8.8) | (6.5)
Equity Securities [Member] | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (23.9) | (43.7)
Equity Securities [Member] | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | 0.0 | 0.0
Trade receivables [member] |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (4.0) | (7.6)
Trade receivables [member] | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (7.9) | (6.9)
Trade receivables [member] | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (21.0) | (18.7)
Other monetary assets [member] | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (17.2) | (20.2)
Other monetary assets [member] | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | 0.6 | (4.1)
Accounts Payable And Accrued Liabilities [Member] | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (83.8) | (71.7)
Accounts Payable And Accrued Liabilities [Member] | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (26.1) | (25.4)
Deferred Income Taxes | Currency risk [member] | Canadian dollar |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | (561.2) | (490.6)
Deferred Income Taxes | Currency risk [member] | Mexican peso |  |
Disclosure of nature and extent of risks arising from financial instruments [line items] |  |
Total financial instrument exposure to credit risk | $ (62.0) | $ (58.2)

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