Restructuring and Other Costs - Schedule of Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring And Related Activities [Abstract]
Restructuring	$ 7.4	$ 6.4	$ 40.1	$ 56.4
Other	2.3	11.5	16.1	50.7
Restructuring and other costs	$ 9.7	$ 17.9	$ 56.2	$ 107.1