Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020
Other assets
Earnest money and refundable deposits	$ 1,440.8		$ 1,079.8
Insurance receivables	112.0		109.5	$ 90.5
Other receivables	151.5		153.6
Prepaid assets	77.2		51.6
Contract assets - insurance agency commissions	64.8		58.6
Lease right of use assets	41.7		35.6
Mortgage servicing rights	5.0		4.1
Mortgage hedging instruments and commitments	171.4		0.0
Other	56.7		49.9
Other assets	2,177.7		1,560.6
Accrued expenses and other liabilities
Reserves for legal claims	617.1		577.5	524.4		$ 473.8
Employee compensation and related liabilities	466.3		492.1
Warranty liability	407.8	$ 390.0	376.3	$ 340.7	$ 324.0	$ 310.2
Customer deposits	283.4		193.4
Inventory related accruals	315.5		261.2
Broker deposits related to hedging instruments	139.3		0.0
Federal and state income tax liabilities	85.4		88.2
Accrued property taxes	30.9		51.0
Lease liabilities	43.2		37.0
Accrued interest	34.1		31.5
Mortgage hedging instruments and commitments	9.8		1.7
Other	97.1		100.4
Accrued expenses and other liabilities	2,618.9		2,210.3
Interest rate lock commitments [Member]
Other assets
Interest rate lock commitments	56.6		17.9
Accrued expenses and other liabilities
Interest rate lock commitments	$ 89.0		$ 0.0