Inventory Impairments and Land Option Cost Write-Offs (Details) (Homebuilding [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Inventory Impairments Information [Line Items]
Carrying value of communities with impairment indicators	$ 359.8	$ 359.8
Impairment charges	18.1	75.2	21.3	3.2
Write-offs (recoveries) of earnest money deposits and pre-acquisition costs		10.0	9.8	3.0
Midwest [Member]
Inventory Impairments Information [Line Items]
Impairment charges		49.3	0	0
East [Member]
Inventory Impairments Information [Line Items]
Impairment charges		$ 17.7	$ 0.1	$ 1.0