Restructuring and Other Costs - Schedule of Changes in Restructuring Accrual Charges (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Restructuring And Other Costs [Abstract]
Accrual at beginning of fiscal year	$ 32.3	$ 31.6
Additional accruals	31.7	37.5
Payments	(35.3)	(32.9)
Adjustment to accruals	(1.1)	(3.1)
Foreign currency rate changes		0.1
Accrual at June 30	$ 27.6	$ 33.2