Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2023	Sep. 30, 2023
Inventories [Abstract]
Finished goods and work in process	$ 1,083.8	$ 1,044.9
Raw materials	1,045.8	1,049.8
Spare parts and supplies	601.7	578.2
Inventories at FIFO cost	2,731.3	2,672.9
LIFO reserve	(340.0)	(341.4)
Net inventories	$ 2,391.3	$ 2,331.5