Intangible Assets, net (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Mar. 31, 2022	Sep. 30, 2021
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross			$ 376.8	$ 376.8
Finite-lived intangible assets, accumulated amortization			(163.5)	(153.7)
Finite-lived intangible assets, net			213.3	223.1
Accelerated amortization	$ 17.7	$ 18.1
Customer relationships
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross			178.6	178.6
Finite-lived intangible assets, accumulated amortization			(80.1)	(75.3)
Finite-lived intangible assets, net			98.5	103.3
Trademarks and brands
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross			195.1	195.1
Finite-lived intangible assets, accumulated amortization			(80.3)	(75.3)
Finite-lived intangible assets, net			114.8	119.8
Other intangible assets
Finite-Lived Intangible Assets
Finite-lived intangible assets, gross			3.1	3.1
Finite-lived intangible assets, accumulated amortization			(3.1)	(3.1)
Finite-lived intangible assets, net			$ 0.0	$ 0.0