Other Income (Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Other Income and Expenses [Abstract]
Interest income	$ 3.5	$ 1.3	$ 8.5	$ 2.6
Royalty income	3.4	3.4	6.2	5.9
Legacy product liability and environmental charges	(2.7)	(3.1)	(7.7)	(5.9)
Non-operating pension and postretirement benefit credit (cost)	4.9	(105.4)	9.8	(93.0)
Other	5.7	(3.3)	6.9	0.6
Other income (expense)	$ 14.8	$ (107.1)	$ 23.7	$ (89.8)