Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Allowance For Doubtful Accounts [Abstract]
Balance at beginning of Year	$ 13.1	$ 17.6	$ 11.8
Charged to Operations	19.2	9.5	11.0
Write-offs	(13.1)	(14.0)	(5.2)
Balance at end of year	$ 19.2	$ 13.1	$ 17.6