Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Revenue from External Customer [Line Items]
Deferred development lot sales	$ 1.7	$ 7.5	$ 3.0	$ 14.3
Tract sales and other	6.2	41.1	6.6	44.4
Revenues	333.8	301.5	639.7	518.2
Real Estate | Residential Real Estate [Member]
Revenue from External Customer [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 325.9	$ 252.9	$ 630.1	$ 459.5