Supplemental Information (Related Party Transactions) (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Related Party Transaction [Line Items]
Sales and other income	$ 80.0	$ 95.0
Trade receivables, net	1,807.4		$ 1,821.6
Current portion of long-term debt	1,131.4		611.4
Related Party
Related Party Transaction [Line Items]
Trade receivables, net	185.0		120.0
Total debt	292.7		304.4
Current portion of long-term debt	$ 192.3		$ 200.0

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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