Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Millions		Sep. 30, 2020	Sep. 30, 2019
Payables And Accruals [Abstract]
Payroll related accruals		$ 59.8	$ 43.9
Accrued operating expenses		84.4	63.9
Other accruals	[1]	53.0	28.2
Accrued expenses and other current liabilities		$ 197.2	$ 136.0

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