Revenues (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022 USD ($) Lot	Jun. 30, 2021 USD ($) Lot	Jun. 30, 2022 USD ($) Lot	Jun. 30, 2021 USD ($) Lot	Sep. 30, 2021 USD ($)
Revenue from External Customer [Line Items]
Deferred development lot sales	$ 7.9	$ 0.0	$ 20.4	$ 0.0
Deferred income	4.1		4.1		$ 6.8
Tract sales and other	5.5	5.5	9.1	12.6
Revenues	$ 308.5	$ 312.9	$ 1,137.7	$ 907.1
Number of Lots Sold | Lot	3,473	3,858	13,777	11,013
Deferred Development Project
Revenue from External Customer [Line Items]
Residential lot sales	$ 9.4		$ 64.1
Deferred development lot sales	$ 1.1
Number of Lots Sold | Lot	67		854
Proceeds from Deposits from Customers	$ 4.6		$ 33.6
Prior Deferred Development Project
Revenue from External Customer [Line Items]
Deferred development lot sales	6.8
Real Estate [Member] | Residential Real Estate [Member]
Revenue from External Customer [Line Items]
Residential lot sales	295.1	$ 307.4	1,108.2	$ 894.5
Revenues	$ 303.0	$ 307.4	$ 1,100.0	$ 894.5