Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended										12 Months Ended
	Sep. 30, 2014		Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013		Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2012
Revenues
Revenues, Total	$ 2,472.3		$ 2,147.0	$ 1,735.0	$ 1,670.6	$ 1,859.8		$ 1,692.8	$ 1,431.6	$ 1,275.1	$ 8,024.9		$ 6,259.3		$ 4,354.0
Income (Loss) before income taxes
Income before income taxes	250.8		171.8	201.9	189.7	202.8		205.1	142.1	107.9	814.2	[1]	657.8	[1]	242.9	[1]
Homebuilding [Member]
Segment Reporting Information [Line Items]
Number of Operating Segments	37
Revenues
Homebuilding revenues											7,858.5		6,085.9		4,236.2
Inventory Impairments
Inventory impairments	18.1										75.2		21.3		3.2
Income (Loss) before income taxes
Income before income taxes											768.8	[1]	592.3	[1]	203.7	[1]
Homebuilding inventories
Total inventories	7,700.5	[2]				6,197.4	[2]				7,700.5	[2]	6,197.4	[2]
Financial Services [Member]
Revenues
Financial Services Revenue											166.4		173.4		117.8
Income (Loss) before income taxes
Income before income taxes											45.4	[1]	65.5	[1]	39.2	[1]
East [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											954.7		686.3		542.4
Inventory Impairments
Inventory impairments											17.7		0.1		1.0
Income (Loss) before income taxes
Income before income taxes											45.2	[1]	48.3	[1]	16.0	[1]
Homebuilding inventories
Total inventories	842.7	[2]				742.9	[2]				842.7	[2]	742.9	[2]
Midwest [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											483.5		471.5		339.3
Inventory Impairments
Inventory impairments											49.3		0		0
Income (Loss) before income taxes
Income before income taxes											(9.5)	[1]	38.9	[1]	1.1	[1]
Homebuilding inventories
Total inventories	477.6	[2]				412.2	[2]				477.6	[2]	412.2	[2]
Southeast [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											2,167.0		1,520.7		934.6
Inventory Impairments
Inventory impairments											3.1		0		1.6
Income (Loss) before income taxes
Income before income taxes											218.0	[1]	148.4	[1]	38.0	[1]
Homebuilding inventories
Total inventories	1,943.0	[2]				1,508.5	[2]				1,943.0	[2]	1,508.5	[2]
South Central [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											1,971.2		1,526.2		1,158.4
Inventory Impairments
Inventory impairments											0		1.0		0.1
Income (Loss) before income taxes
Income before income taxes											208.0	[1]	149.0	[1]	80.6	[1]
Homebuilding inventories
Total inventories	1,742.5	[2]				1,443.6	[2]				1,742.5	[2]	1,443.6	[2]
Southwest [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											285.2		327.7		270.7
Inventory Impairments
Inventory impairments											0		0		0.5
Income (Loss) before income taxes
Income before income taxes											25.5	[1]	26.3	[1]	16.8	[1]
Homebuilding inventories
Total inventories	292.9	[2]				262.4	[2]				292.9	[2]	262.4	[2]
West [Member] | Homebuilding [Member]
Revenues
Homebuilding revenues											1,996.9		1,553.5		990.8
Inventory Impairments
Inventory impairments											5.1		20.2		0
Income (Loss) before income taxes
Income before income taxes											281.6	[1]	181.4	[1]	51.2	[1]
Homebuilding inventories
Total inventories	2,169.4	[2]				1,668.2	[2]				2,169.4	[2]	1,668.2	[2]
Corporate and unallocated [Member] | Homebuilding [Member]
Homebuilding inventories
Total inventories	$ 232.4	[2],[3]				$ 159.6	[2],[3]				$ 232.4	[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.