Accounting Policies (Details) - USD ($) $ in Millions			12 Months Ended
	Sep. 30, 2022	Oct. 05, 2017	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 7.3		$ 7.3	$ 3.8
Accumulated depreciation	(1.6)		(1.6)	(0.9)
Property and equipment, net	$ 5.7		5.7	2.9
Depreciation			$ 0.7	0.4	$ 0.3
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			4 years 6 months
Majority Shareholder [Member] | D.R. Horton, Inc. [Member]
Property, Plant and Equipment [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	63.00%	75.00%
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 1.5		$ 1.5	0.9
Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 5.8		$ 5.8	$ 2.9
Maximum | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life			10 years
Maximum | Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life			10 years
Minimum | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life			5 years
Minimum | Property, Plant and Equipment, Other Types [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life			2 years