Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Sep. 30, 2014
Homebuilding revenues:
Consolidated revenues	$ 2,302.6		$ 1,670.6
Income (Loss) before Income Taxes
Income (loss) before income taxes	220.7	[1]	189.7	[1]
Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	2,253.0		1,635.6
Asset Impairment Charges [Abstract]
Inventory Write-down	3.8		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	206.1	[1]	181.9	[1]
Homebuilding inventories
Total homebuilding inventory	7,989.3	[2]			7,700.5	[2]
Financial Services [Member]
Homebuilding revenues:
Financial Services Revenue	49.6		35.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	14.6	[1]	7.8	[1]
East [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	298.7		190.1
Asset Impairment Charges [Abstract]
Inventory Write-down	0		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	26.3	[1]	11.5	[1]
Homebuilding inventories
Total homebuilding inventory	868.8	[2]			842.7	[2]
Midwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	130.0		105.8
Asset Impairment Charges [Abstract]
Inventory Write-down	0		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	4.8	[1]	10.0	[1]
Homebuilding inventories
Total homebuilding inventory	501.9	[2]			477.6	[2]
Southeast [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	619.4		447.3
Asset Impairment Charges [Abstract]
Inventory Write-down	0		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	58.0	[1]	51.5	[1]
Homebuilding inventories
Total homebuilding inventory	2,026.4	[2]			1,943.0	[2]
South Central [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	579.7		421.1
Asset Impairment Charges [Abstract]
Inventory Write-down	0		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	61.2	[1]	42.4	[1]
Homebuilding inventories
Total homebuilding inventory	1,873.6	[2]			1,742.5	[2]
Southwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	75.4		70.7
Asset Impairment Charges [Abstract]
Inventory Write-down	0		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	1.9	[1]	6.0	[1]
Homebuilding inventories
Total homebuilding inventory	291.6	[2]			292.9	[2]
West [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	549.8		400.6
Asset Impairment Charges [Abstract]
Inventory Write-down	3.8		0
Income (Loss) before Income Taxes
Income (loss) before income taxes	53.9	[1]	60.5	[1]
Homebuilding inventories
Total homebuilding inventory	2,183.7	[2]			2,169.4	[2]
Corporate and Unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total homebuilding inventory	$ 243.3	[2],[3]			$ 232.4	[2],[3]

[1] Expenses maintained at the corporate level consist primarily of interest and property taxes, which are capitalized and amortized to cost of sales or expensed directly, and the expenses related to operating the Company’s corporate office. The amortization of capitalized interest and property taxes is allocated to each segment based on the segment’s revenue, while those expenses associated with the corporate office are allocated to each segment based on the segment’s inventory balances.

[2] Homebuilding inventories are the only assets included in the measure of homebuilding segment assets used by the Company’s chief operating decision makers.

[3] Corporate and unallocated consists primarily of capitalized interest and property taxes.