Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Homebuilding revenues:
Consolidated revenues		$ 2,950.8	$ 2,147.0	$ 7,651.6	$ 5,552.5
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	333.8	171.8	784.6	563.4
Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		2,876.4	2,102.9	7,468.0	5,435.1
Asset Impairment Charges [Abstract]
Inventory Write-down		11.7	54.7	23.6	57.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	302.1	158.6	716.8	532.2
Homebuilding inventories
Total homebuilding inventory	[2]	8,111.2		8,111.2		$ 7,700.5
Financial Services [Member]
Homebuilding revenues:
Financial Services Revenue		74.4	44.1	183.6	117.4
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	31.7	13.2	67.8	31.2
East [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		367.4	251.3	946.9	644.6
Asset Impairment Charges [Abstract]
Inventory Write-down		2.1	2.0	2.1	2.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	30.3	13.3	69.7	39.0
Homebuilding inventories
Total homebuilding inventory	[2]	855.1		855.1		842.7
Midwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		205.4	133.1	480.3	338.8
Asset Impairment Charges [Abstract]
Inventory Write-down		0.0	48.8	0.0	48.8
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	21.5	(37.2)	36.5	(18.1)
Homebuilding inventories
Total homebuilding inventory	[2]	485.1		485.1		477.6
Southeast [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		775.5	584.4	2,041.0	1,503.0
Asset Impairment Charges [Abstract]
Inventory Write-down		1.4	0.7	8.7	2.8
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	80.7	52.3	197.4	156.0
Homebuilding inventories
Total homebuilding inventory	[2]	1,966.5		1,966.5		1,943.0
South Central [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		715.1	533.3	1,923.1	1,384.9
Asset Impairment Charges [Abstract]
Inventory Write-down		0.8	0.0	1.4	0.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	78.9	54.0	205.1	143.0
Homebuilding inventories
Total homebuilding inventory	[2]	1,962.2		1,962.2		1,742.5
Southwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		96.7	74.1	243.0	207.8
Asset Impairment Charges [Abstract]
Inventory Write-down		0.0	0.0	0.0	0.0
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	5.2	8.2	8.3	19.7
Homebuilding inventories
Total homebuilding inventory	[2]	280.0		280.0		292.9
West [Member] | Homebuilding [Member]
Homebuilding revenues:
Total homebuilding revenues		716.3	526.7	1,833.7	1,356.0
Asset Impairment Charges [Abstract]
Inventory Write-down		7.4	3.2	11.4	3.4
Income (Loss) before Income Taxes
Income (loss) before income taxes	[1]	85.5	$ 68.0	199.8	$ 192.6
Homebuilding inventories
Total homebuilding inventory	[2]	2,307.4		2,307.4		2,169.4
Corporate and Unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total homebuilding inventory	[2],[3]	$ 254.9		$ 254.9		$ 232.4

[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 cost of sales, 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.