Basis of Presentation and Summary of Significant Accounting Policies (Details) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2016 home	Sep. 30, 2016	Sep. 30, 2016 home	Sep. 30, 2016 lot	Sep. 30, 2016	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Summary of Significant Accounting Policies [Line Items]
Threshold number of homes below a minimum threshold of profitability	10		10	10
Measurement threshold of likelihood of being realized (percent)					50.00%
Advertising costs						$ 19.2	$ 18.0	$ 17.8
Minimum
Summary of Significant Accounting Policies [Line Items]
Estimated time to develop, sell, construct and close all homes (in years)		3 years
Estimated future warranty costs as a percentage or revenue (percent)					0.44%
Minimum | Buildings
Summary of Significant Accounting Policies [Line Items]
Estimated useful life		25 years
Minimum | Furniture, Fixtures, Computer and Office Equipment
Summary of Significant Accounting Policies [Line Items]
Estimated useful life		3 years
Maximum
Summary of Significant Accounting Policies [Line Items]
Estimated time to develop, sell, construct and close all homes (in years)		5 years
Estimated future warranty costs as a percentage or revenue (percent)					1.238%
Maximum | Buildings
Summary of Significant Accounting Policies [Line Items]
Estimated useful life		30 years
Maximum | Information systems
Summary of Significant Accounting Policies [Line Items]
Estimated useful life		5 years
Maximum | Furniture, Fixtures, Computer and Office Equipment
Summary of Significant Accounting Policies [Line Items]
Estimated useful life		7 years