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Derivative Financial Instruments - Additional Information (Details) - CAD ($) $ in Millions | Oct. 18, 2018 | Sep. 28, 2018 | Sep. 30, 2018 | Sep. 30, 2017
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Canadian Dollar Forward Contract |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative cost of hedge |  | $ 30.0 |  |
Foreign currency forward contract term |  | 90 days |  |
Canadian Dollar Forward Contract | Subsequent Event |  |  |  |
Derivative [Line Items] |  |  |  |
Derivative cost of hedge | $ 20.0 |  |  |
Canadian Subsidiary |  |  |  |
Derivative [Line Items] |  |  |  |
Denominated intercompany accounts payable |  |  | $ 20.4 | $ 26.1

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- Definition Period the derivative contract is outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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