Restructuring and Other Costs - Schedule of Restructuring and Other Costs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Restructuring And Related Activities [Abstract]
Restructuring	$ 8.0	$ 24.3	$ 32.7	$ 50.0
Other	8.4	10.5	13.8	39.2
Restructuring and other costs	$ 16.4	$ 34.8	$ 46.5	$ 89.2