Allowance for Doubtful Accounts - Allowance for Bad Debts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of year	$ 39.8	$ 27.1	$ 48.6
Provision for bad debts	12.4	10.4	13.0
Allowance charge-offs	(5.6)	(5.9)	(35.6)
Other	1.2	0.0	1.1
Balance, end of year	47.8	39.8	$ 27.1	$ 48.6
Bad debt expense not included in allowance	3.4
Accounting Standards Update [Extensible Enumeration]			Accounting Standards Update 2016-13 [Member]	Accounting Standards Update 2018-02 [Member]	Accounting Standards Update 2018-02 [Member]
Cumulative transition adjustment
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of year	0.0	8.2	$ 0.0
Balance, end of year		0.0	8.2	$ 0.0
Adjusted balance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of year	$ 39.8	35.3	48.6
Balance, end of year		$ 39.8	$ 35.3	$ 48.6