Assets and Liabilities, at Fair Value - Narrative (Details) - USD ($)	Mar. 31, 2023	Sep. 30, 2022	Jun. 11, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities	$ 513,800,000	$ 400,600,000
Carrying value	340,600,000	339,100,000
Contingent Consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Accounts payable and other accrued liabilities	$ 0	$ 0
Senior Secured Notes due 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt instrument, interest rate, stated percentage	8.625%		8.625%
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	$ 351,900,000