Income Taxes - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Income Taxes [Line Items]
Income tax benefit	$ (30.1)	$ (4.6)	$ (5.6)
Unrecognized tax benefits	0.0	0.0
Carryback claim refunded	0.0	(0.8)	(0.3)
Increase to the valuation allowance	1.2
Valuation allowance	$ 6.3	$ 5.1
State
Income Taxes [Line Items]
Tax examination	2019
Net operating losses	$ 90.9
Net operating losses, expiration start year	2025
Interest expense carryforward	$ 94.6
Valuation allowance	$ 6.3
U.S. federal
Income Taxes [Line Items]
Tax examination	2020
Interest expense carryforward	$ 58.4
Cares Act
Income Taxes [Line Items]
Income taxes receivable	39.0
Income tax benefit	10.1
Income tax credit related to employee retention	1.0		$ 3.3
Carryback claim refunded	$ 8.4