Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenue from External Customer [Line Items]
Deferred development lot sales	$ 10.3	$ 7.9	$ 24.6	$ 20.4
Tract sales and other	23.8	5.5	68.2	9.1
Revenues	368.9	308.5	887.1	1,137.7
Real Estate | Residential Real Estate [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 334.8	$ 295.1	$ 794.3	$ 1,108.2