v3.26.1
Notes Payable - Financial Services Textuals (Details) - USD ($)
$ in Millions
6 Months Ended
Mar. 31, 2026
Sep. 30, 2025
Debt Instrument [Line Items]    
Notes payable $ 6,563.8 $ 5,965.5
Financial Services [Member]    
Debt Instrument [Line Items]    
Notes payable 1,478.2 1,408.3
Commitments to Extend Credit | Financial Services [Member]    
Debt Instrument [Line Items]    
Line of Credit Facility, Current Borrowing Capacity $ 1,400.0  
Line of Credit Facility, Expiration Date May 06, 2026  
Line of Credit Facility, Maximum Borrowing Capacity $ 2,000.0  
Notes payable $ 1,062.1 1,103.5
Assets Sold under Agreements to Repurchase, Interest Rate 5.40%  
Deposit Liabilities, Collateral Issued, Financial Instruments $ 2,310.0  
Participating Mortgage Loans, Mortgage Obligations, Amount 2,260.0  
Warehouse Agreement Borrowings | Financial Services [Member]    
Debt Instrument [Line Items]    
Line of Credit Facility, Current Borrowing Capacity 500.0  
Notes payable $ 416.1 $ 304.8
Assets Sold under Agreements to Repurchase, Interest Rate 4.90%  
Deposit Liabilities, Collateral Issued, Financial Instruments $ 464.6  
Participating Mortgage Loans, Mortgage Obligations, Amount $ 430.7