Real Estate - Text (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2023 |
|
| Real Estate Properties [Line Items] | |||
| Real estate | $ 2,645.1 | $ 2,266.2 | |
| Payments to Acquire Residential Real Estate | 595.3 | ||
| Payments to Develop Real Estate Assets | 1,100.0 | ||
| Asset Impairment Charges | 0.0 | 0.0 | $ 19.4 |
| Loss on Contract Termination | 7.2 | 4.1 | $ 4.6 |
| Developed and under development projects | |||
| Real Estate Properties [Line Items] | |||
| Real estate | 2,465.1 | 2,126.1 | |
| Land held for future development | |||
| Real Estate Properties [Line Items] | |||
| Real estate | $ 180.0 | $ 140.1 | |
| D.R. Horton, Inc. [Member] | Minimum | |||
| Real Estate Properties [Line Items] | |||
| Related Party Transaction, Rate | 12.00% | ||
| D.R. Horton, Inc. [Member] | Maximum | |||
| Real Estate Properties [Line Items] | |||
| Related Party Transaction, Rate | 16.00% | ||