Related Party Transactions (Details) $ in Millions | 3 Months Ended | 6 Months Ended | |
Mar. 31, 2021USD ($)Lot | Mar. 31, 2020USD ($)Lot | Mar. 31, 2021USD ($)Lot | Mar. 31, 2020USD ($)Lot | Sep. 30, 2020USD ($)Lot |
Related Party Transaction [Line Items] | | | | | |
Number of Units in Real Estate Property | Lot | 84,500 | | 84,500 | | 60,500 |
Number of Lots Sold | Lot | 3,588 | 1,951 | 7,155 | 4,373 | |
Real estate | $ 1,698.6 | | $ 1,698.6 | | $ 1,309.7 |
Inventory, Land Held for Development and Sale | 55.5 | | 55.5 | | 5.4 |
Revenues | 287.1 | $ 159.1 | 594.2 | $ 406.4 | |
D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Due to Related Parties, Current | 1.1 | | 1.1 | | $ 8.4 |
Deferred Revenue, Period Increase (Decrease) | (0.2) | 0.8 | | (0.6) | |
Related Party Transaction, Purchases from Related Party | $ 1.2 | $ 1.5 | 2.9 | 2.9 | |
Related Party Transaction, Selling, General and Administrative Expenses from Transactions with Related Party | | | 2 | 2.6 | |
Related Party Transaction, Expenses from Transactions with Related Party | | | 1.8 | 1 | |
Costs and Expenses, Related Party | | | $ 1.4 | $ 1.3 | |
D.R. Horton, Inc. [Member] | Maximum [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Transaction, Rate | | | 16.00% | | |
D.R. Horton, Inc. [Member] | Minimum [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Transaction, Rate | | | 12.00% | | |
D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Number of Lots Sold | Lot | 3,358 | 1,906 | 6,747 | 4,296 | |
Revenue from Related Parties | $ 265.6 | $ 151.2 | $ 559.6 | $ 366.8 | |
Under Contract [Member] | D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Number of Units in Real Estate Property | Lot | 20,400 | | 20,400 | | 14,000 |
Related Party Transaction, Purchase Obligation from Parent | $ 1,505.3 | | $ 1,505.3 | | $ 1,022.2 |
Under Contract [Member] | D.R. Horton, Inc. [Member] | Notes Payable, Other Payables | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Deposit Liabilities | 2.6 | | 2.6 | | 4.8 |
Under Contract [Member] | D.R. Horton, Inc. [Member] | Cash | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Deposit Liabilities | $ 134.1 | | $ 134.1 | | $ 92.2 |
Right of First Offer [Member] | D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Number of Units in Real Estate Property | Lot | 16,700 | | 16,700 | | 16,400 |
Other Expense [Member] | D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Transaction, Amounts of Transaction | $ 7.3 | 8.2 | $ 28.2 | 13.3 | |
Deposits [Member] | D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Related Party Transaction, Amounts of Transaction | $ 8 | $ 5.5 | $ 24.2 | $ 16.2 | |
Land [Member] | D.R. Horton, Inc. [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Number of Lots Sold | Lot | 14 | 0 | 14 | 36 | |
Revenue from Related Parties | $ 3 | $ 0 | $ 3 | $ 7.2 | |
Real Estate [Member] | | | | | |
Related Party Transaction [Line Items] | | | | | |
Revenues | $ 280.2 | $ 156.4 | $ 587.1 | $ 373.5 | |