Segment Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Sep. 30, 2015
Homebuilding revenues:
Total revenues		$ 3,231.9	$ 2,950.8	$ 8,416.2	$ 7,651.6
Income Before Income Taxes
Income before income taxes	[1]	378.6	333.8	920.4	784.6
Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		3,148.8	2,876.4	8,210.8	7,468.0
Inventory Impairments
Total inventory impairments		5.2	11.7	8.9	23.6
Income Before Income Taxes
Income before income taxes		349.2	302.1	861.3	716.8
Homebuilding Inventories
Total homebuilding inventories	[2]	8,504.2		8,504.2		$ 7,807.0
Financial Services [Member]
Homebuilding revenues:
Financial services revenues		83.1	74.4	205.4	183.6
Income Before Income Taxes
Income before income taxes		29.4	31.7	59.1	67.8
Operating Segments [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		3,148.8	2,876.4	8,210.8	7,468.0
Inventory Impairments
Total inventory impairments		5.2	11.7	8.9	23.6
Income Before Income Taxes
Income before income taxes	[1]	349.2	302.1	861.3	716.8
Operating Segments [Member] | Financial Services [Member]
Homebuilding revenues:
Financial services revenues		83.1	74.4	205.4	183.6
Income Before Income Taxes
Income before income taxes		29.4	31.7	59.1	67.8
Reportable Geographical Components [Member] | East [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		391.2	367.4	998.3	946.9
Inventory Impairments
Total inventory impairments		4.2	2.1	7.4	2.1
Income Before Income Taxes
Income before income taxes	[1]	40.4	30.3	90.9	69.7
Homebuilding Inventories
Total homebuilding inventories	[2]	879.6		879.6		817.3
Reportable Geographical Components [Member] | Midwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		179.9	205.4	465.2	480.3
Inventory Impairments
Total inventory impairments		0.0	0.0	0.0	0.0
Income Before Income Taxes
Income before income taxes	[1]	13.5	21.5	29.5	36.5
Homebuilding Inventories
Total homebuilding inventories	[2]	457.4		457.4		474.5
Reportable Geographical Components [Member] | Southeast [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		913.3	775.5	2,436.9	2,041.0
Inventory Impairments
Total inventory impairments		0.0	1.4	0.2	8.7
Income Before Income Taxes
Income before income taxes	[1]	107.8	80.7	279.5	197.4
Homebuilding Inventories
Total homebuilding inventories	[2]	2,046.9		2,046.9		1,876.7
Reportable Geographical Components [Member] | South Central [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		816.1	715.1	2,123.4	1,923.1
Inventory Impairments
Total inventory impairments		1.0	0.8	1.0	1.4
Income Before Income Taxes
Income before income taxes	[1]	109.5	78.9	263.1	205.1
Homebuilding Inventories
Total homebuilding inventories	[2]	2,125.8		2,125.8		1,909.0
Reportable Geographical Components [Member] | Southwest [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		93.0	96.7	246.8	243.0
Inventory Impairments
Total inventory impairments		0.0	0.0	0.0	0.0
Income Before Income Taxes
Income before income taxes	[1]	0.9	5.2	5.6	8.3
Homebuilding Inventories
Total homebuilding inventories	[2]	363.9		363.9		312.4
Reportable Geographical Components [Member] | West [Member] | Homebuilding [Member]
Homebuilding revenues:
Homebuilding revenues		755.3	716.3	1,940.2	1,833.7
Inventory Impairments
Total inventory impairments		0.0	7.4	0.3	11.4
Income Before Income Taxes
Income before income taxes	[1]	77.1	$ 85.5	192.7	$ 199.8
Homebuilding Inventories
Total homebuilding inventories	[2]	2,372.3		2,372.3		2,165.3
Corporate and Unallocated [Member] | Homebuilding [Member]
Homebuilding Inventories
Total homebuilding inventories	[2],[3]	$ 258.3		$ 258.3		$ 251.8

[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.