Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Other assets
Earnest money and refundable deposits	$ 1,278.9	$ 1,079.8
Insurance receivables	107.0	109.5	$ 82.2
Other receivables	154.3	153.6
Prepaid assets	70.4	51.6
Contract assets - insurance agency commissions	60.8	58.6
Lease right of use assets	38.1	35.6
Mortgage servicing rights	8.3	4.1
Other	45.1	49.9
Other assets	1,787.5	1,560.6
Accrued expenses and other liabilities
Reserves for legal claims	585.2	577.5	491.8	$ 473.8
Employee compensation and related liabilities	428.1	492.1
Warranty liability	390.0	376.3	$ 324.0	$ 310.2
Customer deposits	218.2	193.4
Inventory related accruals	274.5	261.2
Federal and state income tax liabilities	430.5	88.2
Accrued property taxes	32.2	51.0
Lease liabilities	39.3	37.0
Accrued interest	37.2	31.5
Other	144.8	102.1
Accrued expenses and other liabilities	2,580.0	2,210.3
Interest rate lock commitments [Member]
Other assets
Interest rate lock commitments	$ 24.6	$ 17.9