v3.25.2
Real Estate - Text (Detail) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Sep. 30, 2024
Real Estate Properties [Line Items]          
Real estate $ 2,823.5   $ 2,823.5   $ 2,266.2
Payments to Acquire Residential Real Estate     532.6    
Payments to Develop Real Estate Assets     864.3    
Asset Impairment Charges     0.0 $ 0.0  
Loss on Contract Termination 1.9 $ 0.7 3.9 $ 1.0  
Developed and under development projects          
Real Estate Properties [Line Items]          
Real estate 2,574.6   2,574.6   2,126.1
Land held for future development          
Real Estate Properties [Line Items]          
Real estate $ 248.9   $ 248.9   $ 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%