Property, Plant, and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	$ 531.0	$ 445.4
Depreciation	78.5	82.9	$ 72.0
Home Building
Property and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(323.0)	(299.2)
Property, Plant and Equipment, Net	500.2	415.0
Rental
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	1.1	2.4
Forestar Group [Member]
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	7.1	5.9
Financial Services [Member]
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	4.0	4.1
Eliminations and Other
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	18.6	18.0
Building and Building Improvements [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	483.2	414.6
2510 Household Furniture [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	171.2	147.0
Furniture and Fixtures | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	111.1	113.5
Land [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 57.7	$ 39.1