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Related Party Disclosures (Details) $ in Millions	3 Months Ended		9 Months Ended
Related Party Disclosures (Details) $ in Millions	Jun. 30, 2026 USD ($) Lot	Jun. 30, 2025 USD ($) Lot	Jun. 30, 2026 USD ($) Lot	Jun. 30, 2025 USD ($) Lot	Sep. 30, 2025 USD ($) Lot
Related Party Transaction [Line Items]
Selling, general and administrative expense	$ 38.3	$ 37.4	$ 112.6	$ 111.8
Number of Units in Real Estate Property \| Lot	62,200		62,200		65,100
Residential lot sales	$ (397.4)	(383.0)	$ (963.9)	(977.3)
Tract sales and other	(9.6)	(7.5)	(90.4)	(14.6)
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Selling, general and administrative expense			5.4
Employee Benefits and Share-Based Compensation			12.1	10.8
Costs and Expenses, Related Party			1.6	0.7
Related Party Transaction, Purchases from Related Party	0.1	0.1	0.4	0.3
Accrued Liabilities and Other Liabilities	2.6		2.6		$ 2.2
D.R. Horton, Inc. [Member] \| Deposits [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	0.7	4.2	4.2	18.8
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] \| Other Preacquisition and Due Diligence Costs [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	$ 7.0	$ 9.5	$ 27.0	$ 17.7
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Number of Lots Sold \| Lot	3,370	3,075	7,447	7,688
Residential lot sales	$ 361.1	$ 325.0	$ 829.2	$ 810.2
Deferred Revenue, Period Increase (Decrease)	(0.6)	(1.3)	$ (0.6)	(0.1)
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	$ 0.5	$ 3.8	$ 20.7	$ 7.7
D.R. Horton, Inc. [Member] \| Under Contract [Member]
Related Party Transaction [Line Items]
Number of Units in Real Estate Property \| Lot	21,800		21,800		22,800
Related Party Deposit Liabilities	$ 195.3		$ 195.3		$ 179.7
Related Party Transaction, Purchase Obligation from Parent	$ 2,095.1		$ 2,095.1		$ 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	19,200		19,200		17,600