Other Assets, Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2020	Oct. 01, 2019	Sep. 30, 2019	Sep. 30, 2018
Other assets
Earnest money and refundable deposits	$ 657.1		$ 540.0
Insurance receivables	81.2		75.1
Other receivables	143.1		103.6
Prepaid assets	46.0		49.6
Margin deposits	16.2		19.6
Contract assets - insurance agency commissions	47.1		39.3
Lease right of use assets	34.7	$ 39.0	0.0
Mortgage servicing rights	17.1		0.0
Other	39.9		37.5
Total other assets	1,113.7		912.8
Accrued expenses and other liabilities
Reserves for legal claims	473.8		434.7	$ 408.1
Employee compensation and related liabilities	376.1		282.1
Warranty liability	310.2		247.3	$ 202.0
Mortgage hedging instruments and loan commitments	16.5		0.0
Accrued interest	35.3		26.3
Federal and state income tax liabilities	42.6		33.4
Inventory related accruals	59.7		61.5
Customer deposits	93.1		57.7
Accrued property taxes	44.1		40.1
Lease liabilities	37.0	$ 40.3	0.0
Other	118.6		95.0
Total accrued expenses and other liabilities	$ 1,607.0		$ 1,278.1
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilities		us-gaap:OtherLiabilities
Interest Rate Lock Commitments
Other assets
Interest rate lock commitments	$ 31.3		$ 19.2
Multifamily [Member]
Other assets
Multi-family rental property held for sale	$ 0.0		$ 28.9