Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2014		Mar. 31, 2013		Sep. 30, 2013
Homebuilding revenues:
Consolidated revenues	$ 1,735.0		$ 1,431.6		$ 3,405.6		$ 2,706.5
Income (Loss) before Income Taxes
Income (loss) before income taxes	201.9	[1]	142.1	[1]	391.6	[1]	250.0	[1]
Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	1,696.6		1,390.4		3,332.3		2,623.5
Income (Loss) before Income Taxes
Income (loss) before income taxes	191.7	[1]	127.4	[1]	373.6	[1]	217.6	[1]
Homebuilding inventories
Total homebuilding inventory	6,783.6	[2]			6,783.6	[2]			6,197.4	[2]
Financial Services [Member]
Homebuilding revenues:
Financial Services Revenue	38.4		41.2		73.3		83.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	10.2	[1]	14.7	[1]	18.0	[1]	32.4	[1]
East [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	203.2		153.8		393.3		291.1
Income (Loss) before Income Taxes
Income (loss) before income taxes	14.2	[1]	8.5	[1]	25.7	[1]	15.5	[1]
Homebuilding inventories
Total homebuilding inventory	763.3	[2]			763.3	[2]			742.9	[2]
Midwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	99.9		92.8		205.7		182.2
Income (Loss) before Income Taxes
Income (loss) before income taxes	9.1	[1]	9.9	[1]	19.1	[1]	7.9	[1]
Homebuilding inventories
Total homebuilding inventory	447.8	[2]			447.8	[2]			412.2	[2]
Southeast [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	471.3		333.2		918.7		624.7
Income (Loss) before Income Taxes
Income (loss) before income taxes	52.2	[1]	28.3	[1]	103.7	[1]	47.7	[1]
Homebuilding inventories
Total homebuilding inventory	1,643.1	[2]			1,643.1	[2]			1,508.5	[2]
South Central [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	430.4		364.0		851.5		674.6
Income (Loss) before Income Taxes
Income (loss) before income taxes	46.6	[1]	32.4	[1]	89.0	[1]	57.6	[1]
Homebuilding inventories
Total homebuilding inventory	1,527.8	[2]			1,527.8	[2]			1,443.6	[2]
Southwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	63.1		79.0		133.8		154.9
Income (Loss) before Income Taxes
Income (loss) before income taxes	5.5	[1]	7.1	[1]	11.5	[1]	16.9	[1]
Homebuilding inventories
Total homebuilding inventory	269.9	[2]			269.9	[2]			262.4	[2]
West [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues	428.7		367.6		829.3		696.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	64.1	[1]	41.2	[1]	124.6	[1]	72.0	[1]
Homebuilding inventories
Total homebuilding inventory	1,920.3	[2]			1,920.3	[2]			1,668.2	[2]
Corporate and Unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total homebuilding inventory	$ 211.4	[2],[3]			$ 211.4	[2],[3]			$ 159.6	[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.