Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021
Other assets
Earnest money and refundable deposits	$ 1,738.8		$ 1,685.7
Mortgage hedging instruments and commitments	68.4		330.2
Water rights and other water-related assets	313.9		286.6
Other receivables	176.9		210.9
Insurance receivables	139.0		137.9	$ 122.3
Asset, Held-for-Sale, Not Part of Disposal Group, Other	65.9		0.0
Prepaid assets	58.1		77.4
Contract assets - insurance agency commissions	85.5		74.3
Lease right of use assets	44.4		46.6
Mortgage servicing rights	20.9		10.6
Other	75.0		52.4
Other assets	2,806.6		2,960.3
Accrued expenses and other liabilities
Reserves for legal claims	796.2		729.1	674.4		$ 577.5
Employee compensation and related liabilities	486.3		524.3
Warranty liability	493.4	$ 474.7	454.3	$ 431.8	$ 407.8	$ 376.3
Inventory related accruals	342.2		403.6
Broker deposits related to hedging instruments	71.1		240.9
Customer deposits	172.8		224.2
Federal and state income tax liabilities	123.9		110.9
Accrued property taxes	48.3		60.1
Lease liabilities	45.7		47.9
Accrued interest	29.6		33.8
Mortgage hedging instruments and commitments	10.0		12.4
Other	139.3		113.3
Accrued expenses and other liabilities	2,766.0		3,138.3
Interest rate lock commitments [Member]
Other assets
Interest rate lock commitments	19.8		47.7
Accrued expenses and other liabilities
Interest rate lock commitments	$ 7.2		$ 183.5