Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2021	Sep. 30, 2020
Payables And Accruals [Abstract]
Payroll related accruals		$ 70.2	$ 59.8
Accrued operating expenses		84.0	84.4
Other accruals (a)	[1]	66.7	53.0
Accrued expenses and other current liabilities		$ 220.9	$ 197.2

[1] Other accruals for the fiscal years ended September 30, 2021 and September 30, 2020 include the Company’s deferral of Federal Insurance Contributions Act (FICA) payroll tax under the CARES Act.