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Related Party Disclosures (Details) $ in Millions	3 Months Ended
Related Party Disclosures (Details) $ in Millions	Dec. 31, 2025 USD ($) Lot	Dec. 31, 2024 USD ($) Lot	Sep. 30, 2025 USD ($) Lot
Related Party Transaction [Line Items]
Selling, general and administrative expense	$ 36.5	$ 36.0
Number of Units in Real Estate Property \| Lot	65,600		65,100
Residential lot sales	$ 235.2	247.4
Tract sales and other	37.8	3.0
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Selling, general and administrative expense	1.8	1.8
Employee Benefits and Share-Based Compensation	4.2	3.5
Costs and Expenses, Related Party	0.5	0.2
Related Party Transaction, Purchases from Related Party	0.2	0.1
Accrued Liabilities and Other Liabilities	6.3		$ 2.2
D.R. Horton, Inc. [Member] \| Deposits [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	1.7	10.0
D.R. Horton, Inc. [Member] \| Other Expense [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 7.8	4.2
D.R. Horton, Inc. [Member] \| Use Rights
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction		$ 2.1
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Number of Lots Sold \| Lot	1,627	2,112
Residential lot sales	$ 183.8	$ 217.4
Deferred Revenue, Period Increase (Decrease)	$ 0.0	1.2
D.R. Horton, Inc. [Member] \| Minimum
Related Party Transaction [Line Items]
Related Party Transaction, Rate	12.00%
D.R. Horton, Inc. [Member] \| Maximum
Related Party Transaction [Line Items]
Related Party Transaction, Rate	16.00%
D.R. Horton, Inc. [Member] \| Land held for future development
Related Party Transaction [Line Items]
Tract sales and other	$ 5.3	$ 2.0
D.R. Horton, Inc. [Member] \| Under Contract [Member]
Related Party Transaction [Line Items]
Number of Units in Real Estate Property \| Lot	22,600		22,800
Related Party Deposit Liabilities	$ 203.1		$ 179.7
Related Party Transaction, Purchase Obligation from Parent	$ 2,022.4		$ 2,000.0
D.R. Horton, Inc. [Member] \| Right of First Offer [Member]
Related Party Transaction [Line Items]
Number of Units in Real Estate Property \| Lot	18,100		17,600