Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Value of Goodwill (Details) - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2021	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Balance at beginning of year		$ 4,500.8	$ 2,130.3
Acquisitions		0.0	2,389.1
Impairment		0.0	(23.7)
Purchase price allocation adjustment	[1]	(52.4)	0.0
Foreign exchange revaluation		9.3	5.1
Balance at End of Year		$ 4,457.7	$ 4,500.8

[1] Refer to Note 3 - Acquisitions