Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023	Jul. 01, 2020
Debt Instrument [Line Items]
Capital lease obligations	$ 49.0	$ 32.0
Long-term Debt and Lease Obligation	3,266.4	3,376.2
Less current portion	(12.8)	(12.3)
Less unamortized debt premium and debt issuance fees	(27.8)	(31.8)
Total long-term debt	3,225.8	3,332.1
Secured Debt | Senior Secured Term Loan Facility due 2027
Debt Instrument [Line Items]
Total long-term debt, including current maturities	$ 841.0	982.0
Stated interest rate of debt	0.25%
Face amount of debt	$ 3.0
Senior Notes | 4.625% Senior Notes due 2026
Debt Instrument [Line Items]
Total long-term debt, including current maturities	791.3	791.3
Senior Notes | 6.500% Senior Notes due 2027
Debt Instrument [Line Items]
Total long-term debt, including current maturities	300.0	300.0
Senior Notes | Senior Notes, 4.375%, Due 2029
Debt Instrument [Line Items]
Total long-term debt, including current maturities	$ 583.7	583.7
Stated interest rate of debt	4.375%
Senior Notes | Senior Notes, 4.750%, Due 2028
Debt Instrument [Line Items]
Stated interest rate of debt			475.00%
Senior Notes | 3.50% Senior Notes due 2029
Debt Instrument [Line Items]
Total long-term debt, including current maturities	$ 701.4	$ 687.2