Capitalized Interest (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2026 |
Mar. 31, 2025 |
|
| Rollforward of capitalized interest | ||||
| Capitalized interest, beginning of period | $ 463.9 | $ 371.5 | $ 438.7 | $ 355.1 |
| Interest incurred | 60.0 | 55.2 | 116.5 | 101.9 |
| Interest charged to cost of sales | (38.1) | (32.2) | (69.4) | (62.5) |
| Capitalized interest, end of period | 485.8 | 394.5 | 485.8 | 394.5 |
| Financial Services [Member] | ||||
| Rollforward of capitalized interest | ||||
| Interest incurred | 4.2 | 7.4 | 8.9 | 15.5 |
| Forestar Group [Member] | ||||
| Rollforward of capitalized interest | ||||
| Interest incurred | 12.4 | 10.6 | 25.0 | 18.8 |
| Rental | ||||
| Rollforward of capitalized interest | ||||
| Interest incurred | $ 10.3 | $ 16.4 | $ 19.4 | $ 28.8 |