Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012		Sep. 30, 2012
Homebuilding revenues:
Consolidated revenues	$ 1,692.8		$ 1,150.0		$ 4,399.4		$ 3,017.8
Income (Loss) before Income Taxes
Income (loss) before income taxes	205.1	[1]	72.2	[1]	455.1	[1]	143.7	[1]
Homebuilding inventories
Total homebuilding inventory	5,911.5				5,911.5				4,165.2
Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	1,644.5		1,116.2		4,268.1		2,937.4
Income (Loss) before Income Taxes
Income (loss) before income taxes	185.4	[1]	58.3	[1]	403.0	[1]	118.0	[1]
Homebuilding inventories
Total homebuilding inventory	5,911.5	[2]			5,911.5	[2]			4,165.2	[2]
Financial Services [Member]
Homebuilding revenues:
Financial Services Revenue	48.3		33.8		131.3		80.4
Income (Loss) before Income Taxes
Income (loss) before income taxes	19.7	[1]	13.9	[1]	52.1	[1]	25.7	[1]
East [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	163.3		140.6		454.4		393.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	11.4	[1]	3.0	[1]	26.9	[1]	9.2	[1]
Homebuilding inventories
Total homebuilding inventory	732.6	[2]			732.6	[2]			572.7	[2]
Midwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	147.6		88.5		329.9		217.9
Income (Loss) before Income Taxes
Income (loss) before income taxes	15.6	[1]	0.7	[1]	23.5	[1]	(7.4)	[1]
Homebuilding inventories
Total homebuilding inventory	396.8	[2]			396.8	[2]			318.1	[2]
Southeast [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	425.6		241.4		1,050.3		651.5
Income (Loss) before Income Taxes
Income (loss) before income taxes	48.5	[1]	11.4	[1]	96.1	[1]	26.9	[1]
Homebuilding inventories
Total homebuilding inventory	1,404.1	[2]			1,404.1	[2]			905.0	[2]
South Central [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	414.5		306.7		1,089.1		833.2
Income (Loss) before Income Taxes
Income (loss) before income taxes	44.7	[1]	23.7	[1]	102.4	[1]	52.1	[1]
Homebuilding inventories
Total homebuilding inventory	1,364.6	[2]			1,364.6	[2]			935.2	[2]
Southwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	86.1		71.3		241.0		180.9
Income (Loss) before Income Taxes
Income (loss) before income taxes	7.7	[1]	4.9	[1]	24.6	[1]	9.6	[1]
Homebuilding inventories
Total homebuilding inventory	249.9	[2]			249.9	[2]			188.6	[2]
West [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	407.4		267.7		1,103.4		660.9
Income (Loss) before Income Taxes
Income (loss) before income taxes	57.5	[1]	14.6	[1]	129.5	[1]	27.6	[1]
Homebuilding inventories
Total homebuilding inventory	1,624.5	[2]			1,624.5	[2]			1,151.3	[2]
Corporate and Unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total homebuilding inventory	$ 139.0	[2],[3]			$ 139.0	[2],[3]			$ 94.3	[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 interest expense and 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 maker.

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