Supplemental Information (Other Noncurrent Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Disclosure Text Block Supplement [Abstract]
Pension benefits	$ 120.0	$ 133.9
Long-term deposits on plant and equipment	0.0	200.0
Deferred tax assets	159.6	135.7
Prepaid tax	22.2	17.0
Investments other than equity method	66.9	66.7
Deferred financing fees	58.8	0.0
Derivative instruments	320.6	74.7
Other	481.8	319.0
Other noncurrent assets	$ 1,229.9	$ 947.0