Basis of Presentation and Accounting Policies - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Accounting Policies [Abstract]
Allowance for doubtful accounts	$ 13.7		$ 13.2
Allowance for certain customer returns, rebates and incentives	$ 10.5		$ 6.7
Antidilutive share-based compensation awards (in shares)	0.3	0.2
Capital expenditures in accounts payable or other current liabilities at period end	$ 27.3	$ 21.5
Outstanding purchase of common stock recorded in accounts payable	$ 1.4	$ 4.2