Supplemental (Summary of Liabilities Resulting from Related Party Transactions) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019
Related Party Transactions [Abstract]
Payables and accrued liabilities	$ 8.9	$ 8.9
Current portion of long-term debt	38.1	37.8
Long-term debt – related party	$ 323.1	$ 320.1

Amount for accounts payable to related parties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant