Inventory (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Inventory Impairments and Land Option Cost Write-Offs [Abstract]
Inventory Write-down	$ 5.0	$ 19.0	$ 3.8	$ 5.6
Write Offs Recoveries Of Earnest Money Deposits And Pre-Acquisition Costs		61.3	$ 66.6	$ 23.0
Carrying Value of Communities Impaired	$ 33.8	$ 33.8