Notes Payable - Financial Services Textuals (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Notes payable, carrying value	$ 5,094.5	$ 6,066.9
Financial Services [Member]
Debt Instrument [Line Items]
Notes payable, carrying value	1,669.6	1,618.3
Financial Services [Member] | Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Mortgage repurchase facility, current capacity	300.0
Participating Mortgage Loans, Mortgage Obligations, Amount	300.9
Notes payable, carrying value	$ 296.3	0.0
Assets Sold under Agreements to Repurchase, Interest Rate	6.60%
Deposit Liabilities, Collateral Issued, Financial Instruments	$ 323.0
Financial Services [Member] | Commitments to Extend Credit
Debt Instrument [Line Items]
Mortgage repurchase facility, current capacity	2,000.0
Line of credit, maximum borrowing capacity	2,300.0
Participating Mortgage Loans, Mortgage Obligations, Amount	2,180.0
Notes payable, carrying value	$ 1,373.3	$ 1,618.3
Assets Sold under Agreements to Repurchase, Interest Rate	6.90%
Deposit Liabilities, Collateral Issued, Financial Instruments	$ 2,220.0