Long-Term Debt - Schedule of Long-Term Debt (Details) - USD ($) $ in Millions	Jun. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Financing costs, net	$ (9.4)	$ (10.6)
Total debt, net	1,348.2	1,342.7
Less: Current portion of long-term debt	12.0	12.0
Long-term debt, net	1,336.2	1,330.7
Series B Term Loan
Debt Instrument [Line Items]
Debt instruments net of original issue discount	1,177.6	1,185.3
Revolving Credit Agreement
Debt Instrument [Line Items]
Debt instruments net of original issue discount	0.0	0.0
Receivables Financing Agreement
Debt Instrument [Line Items]
Debt instruments net of original issue discount	$ 180.0	$ 168.0