Derivative Financial Instruments - Additional Information (Details) - CAD ($) $ in Millions	9 Months Ended	12 Months Ended
Jun. 30, 2020	Sep. 30, 2019
Canadian Dollar Forward Contract
Derivative [Line Items]
Foreign currency forward contract to hedge	$ 2.0	$ 7.0
Canadian Subsidiary
Derivative [Line Items]
Denominated intercompany accounts payable	$ 3.8	$ 9.3

Amount for accounts payable to related parties.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant