Capitalized Interest (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Capitalized Interest Costs [Line Items]
Interest Costs Incurred	$ 8.2	$ 11.5
Real Estate Inventory, Capitalized Interest Costs	52.9	51.0	$ 53.7	$ 48.7
Real Estate Inventory, Capitalized Interest Costs, Cost of Sales	$ (9.0)	$ (9.2)