Other Assets and Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Homebuilding other assets
Homebuilding other assets	$ 496.1	$ 499.6
Homebuilding [Member]
Homebuilding other assets
Insurance receivables	84.7	88.7	$ 127.8
Earnest money and refundable deposits	228.9	219.7
Accounts and notes receivable	31.0	35.9
Prepaid assets	24.0	29.5
Rental properties	52.7	56.9
Other assets	23.4	25.5
Homebuilding other assets	444.7	456.2
Homebuilding accrued expenses and other liabilities
Reserves for legal claims	435.6	423.5	458.9	$ 451.0
Employee compensation and related liabilities	147.8	183.3
Warranty liability	107.8	104.4	$ 84.1	$ 82.0
Accrued interest	40.3	17.9
Federal and state income tax liabilities	100.7	28.1
Inventory related accruals	32.1	31.9
Homebuyer deposits	45.7	54.2
Accrued property taxes	24.1	35.2
Other liabilities	33.5	38.6
Homebuilding accrued expenses and other liabilities	$ 967.6	$ 917.1