Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2023	Sep. 30, 2022
Schedule of Other Assets, Accrued Expenses and Other Liabilities [Line Items]
Receivables, net	$ 19.1	$ 11.4
Lease right of use assets	7.5	7.5
Prepaid expenses	16.8	18.9
Land purchase contract deposits	7.3	10.0
Income taxes receivable	1.2	0.0
Other assets	$ 3.6	$ 1.8
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets	Other Assets
Other Assets	$ 55.5	$ 49.6
Accrued employee compensation and benefits	6.4	11.6
Accrued property taxes	2.8	6.2
Lease liabilities	8.1	8.1
Accrued interest	6.7	8.0
Contract liabilities	11.4	16.1
Deferred income	4.1	4.1
Income taxes payable	1.2	8.2
Other accrued expenses	4.5	6.8
Other liabilities	$ 2.9	$ 1.0
Operating Lease, Liability, Statement of Financial Position [Extensible List]	Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities
Accrued Liabilities	$ 48.1	$ 70.1
Deferred Development Project
Schedule of Other Assets, Accrued Expenses and Other Liabilities [Line Items]
Contract liabilities	$ 8.0	$ 12.0