Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Sep. 30, 2013		Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2011
Revenues
Revenues, Total	$ 1,859.8		$ 1,692.8	$ 1,431.6	$ 1,275.1	$ 1,336.2		$ 1,150.0	$ 961.2	$ 906.6	$ 6,259.3		$ 4,354.0		$ 3,636.8
Income (Loss) before income taxes
Income before income taxes	202.8		205.1	142.1	107.9	99.2		72.2	42.3	29.2	657.8	[1]	242.9	[1]	12.1	[1]
Homebuilding [Member]
Segment Reporting Information [Line Items]
Number of Operating Segments											34
Revenues
Homebuilding revenues											6,085.9		4,236.2		3,549.6
Inventory Impairments
Inventory impairments	21.3										21.3		3.2		37.3
Income (Loss) before income taxes
Income before income taxes											592.3	[1]	203.7	[1]	(7.0)	[1]
Homebuilding inventories
Total inventories	6,197.4	[2]				4,165.2	[2]				6,197.4	[2]	4,165.2	[2]
Financial Services [Member]
Revenues
Financial Services Revenue											173.4		117.8		87.2
Income (Loss) before income taxes
Income before income taxes											65.5	[1]	39.2	[1]	19.1	[1]
East [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											686.3		542.4		438.5
Inventory Impairments
Inventory impairments											0.1		1.0		3.5
Income (Loss) before income taxes
Income before income taxes											48.3	[1]	16.0	[1]	(13.5)	[1]
Homebuilding inventories
Total inventories	742.9	[2]				572.7	[2]				742.9	[2]	572.7	[2]
Midwest [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											471.5		339.3		261.5
Inventory Impairments
Inventory impairments											0		0		0.1
Income (Loss) before income taxes
Income before income taxes											38.9	[1]	1.1	[1]	(13.7)	[1]
Homebuilding inventories
Total inventories	412.2	[2]				318.1	[2]				412.2	[2]	318.1	[2]
Southeast [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											1,520.7		934.6		696.8
Inventory Impairments
Inventory impairments											0		1.6		15.8
Income (Loss) before income taxes
Income before income taxes											148.4	[1]	38.0	[1]	(19.9)	[1]
Homebuilding inventories
Total inventories	1,508.5	[2]				905.0	[2]				1,508.5	[2]	905.0	[2]
South Central [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											1,526.2		1,158.4		1,081.0
Inventory Impairments
Inventory impairments											1.0		0.1		0.2
Income (Loss) before income taxes
Income before income taxes											149.0	[1]	80.6	[1]	52.4	[1]
Homebuilding inventories
Total inventories	1,443.6	[2]				935.2	[2]				1,443.6	[2]	935.2	[2]
Southwest [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											327.7		270.7		234.8
Inventory Impairments
Inventory impairments											0		0.5		4.4
Income (Loss) before income taxes
Income before income taxes											26.3	[1]	16.8	[1]	(3.8)	[1]
Homebuilding inventories
Total inventories	262.4	[2]				188.6	[2]				262.4	[2]	188.6	[2]
West [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											1,553.5		990.8		837.0
Inventory Impairments
Inventory impairments											20.2		0		13.3
Income (Loss) before income taxes
Income before income taxes											181.4	[1]	51.2	[1]	(8.5)	[1]
Homebuilding inventories
Total inventories	1,668.2	[2]				1,151.3	[2]				1,668.2	[2]	1,151.3	[2]
Corporate and unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total inventories	$ 159.6	[2],[3]				$ 94.3	[2],[3]				$ 159.6	[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.