Other Assets and Accrued Expenses and Other Liabilities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011
Homebuilding other assets
Homebuilding other assets	$ 503.1		$ 507.3
Homebuilding [Member]
Homebuilding other assets
Insurance receivables	195.8		225.0
Earnest money and refundable deposits	87.0		80.0
Accounts and notes receivable	18.0		21.9
Prepaid assets	34.4		29.4
Other Investments	18.6		0
Other assets	102.4		100.5
Homebuilding other assets	456.2		456.8
Homebuilding accrued expenses and other liabilities
Construction defect and other litigation liabilities	519.7		544.9
Employee compensation and related liabilities	114.1		106.4
Warranty liability	57.3	56.6	56.8	48.9	46.0	46.2
Accrued interest	36.1		32.6
Federal and state income tax liabilities	48.6		21.6
Other liabilities	131.4		131.5
Homebuilding accrued expenses and other liabilities	$ 907.2		$ 893.8