Restructuring and Other Costs - Schedule of Changes in Restructuring Accrual Charges (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Restructuring And Other Costs [Abstract]
Accrual at beginning of fiscal year	$ 13.4	$ 17.2
Additional accruals	17.6	8.3
Payments	(4.0)	(10.4)
Adjustment to accruals	(0.3)	(2.5)
Foreign currency rate changes and other		0.1
Accrual at March 31	$ 26.7	$ 12.7