Property, Plant, and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	$ 445.4	$ 471.6
Depreciation	82.9	72.0	$ 73.3
Home Building
Property and Equipment [Line Items]
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment	(299.2)	(289.2)
Property, Plant and Equipment, Net	415.0	361.8
Rental
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	2.4	2.0
Forestar Group [Member]
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	5.9	5.7
Financial Services [Member]
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	4.1	4.3
Eliminations and Other
Property and Equipment [Line Items]
Property, Plant and Equipment, Net	18.0	97.8
Building and Building Improvements [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	414.6	349.6
2510 Household Furniture [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	147.0	133.4
Furniture and Fixtures | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	113.5	132.5
Land [Member] | Home Building
Property and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 39.1	$ 35.5