Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Balance at beginning of year	$ 5,778.6	$ 4,457.7
Acquisitions	152.6	1,367.6
Purchase price allocation adjustment	62.0	(9.3)
Foreign exchange revaluation	10.6	(37.4)
Balance at End of Year	$ 6,003.8	$ 5,778.6