Related Party Disclosures (Details) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2023 USD ($) Lot	Mar. 31, 2022 USD ($) Lot	Mar. 31, 2023 USD ($) Lot	Mar. 31, 2022 USD ($) Lot	Sep. 30, 2022 USD ($) Lot
Related Party Transaction [Line Items]
Selling, General and Administrative Expense	$ 22.0	$ 24.3	$ 44.9	$ 45.8
Costs and Expenses, Related Party			$ 0.9	$ 1.4
Number of Units in Real Estate Property | Lot	57,800		57,800		61,800
Number of Lots Sold | Lot	2,979	5,788	5,242	10,304
Revenues	$ 301.5	$ 421.6	$ 518.2	$ 829.2
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Selling, General and Administrative Expense			1.9	2.0
Employee Benefits and Share-Based Compensation			4.2	3.3
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Deferred Revenue, Period Increase (Decrease)	0.7	(0.5)	3.4	1.6
Related Party Transaction, Purchases from Related Party	0.3	0.7	0.5	1.6
Accrued Liabilities and Other Liabilities	3.0		3.0		$ 3.2
D.R. Horton, Inc. [Member] | Deposits [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction		2.7	0.1	5.4
D.R. Horton, Inc. [Member] | Other Expense [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction	5.7	16.2	10.4	37.8
Residential Real Estate [Member] | Real Estate
Related Party Transaction [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	$ 252.9	$ 409.0	$ 459.5	$ 813.1
D.R. Horton, Inc. [Member]
Related Party Transaction [Line Items]
Number of Lots Sold | Lot	2,666	4,771	4,760	8,785
Revenues	$ 219.9	$ 390.2	$ 407.0	$ 718.2
D.R. Horton, Inc. [Member] | Land held for future development
Related Party Transaction [Line Items]
Number of Lots Sold | Lot	379	0	379	0
Revenues	$ 32.5	$ 0.0	$ 32.5	$ 0.0
D.R. Horton, Inc. [Member] | Under Contract [Member]
Related Party Transaction [Line Items]
Number of Units in Real Estate Property | Lot	14,200		14,200		17,800
Related Party Transaction, Purchase Obligation from Parent	$ 1,246.7		$ 1,246.7		$ 1,389.7
D.R. Horton, Inc. [Member] | Under Contract [Member] | Cash [Member]
Related Party Transaction [Line Items]
Related Party Deposit Liabilities	$ 122.4		$ 122.4		$ 130.1
D.R. Horton, Inc. [Member] | Right of First Offer [Member]
Related Party Transaction [Line Items]
Number of Units in Real Estate Property | Lot	17,300		17,300		18,900