Inventory - Recoverability Schedule of Inventory assets Held for Development, by Reportable Segment (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2017 USD ($) home Community	Sep. 30, 2017 USD ($) lot Community	Sep. 30, 2016 USD ($) Community	Sep. 30, 2015 Community
Real Estate Properties [Line Items]
Number of Communities on Watch List	6	6	14
Number of Communities	2	2	7	0
Pre-analysis Book Value (BV) | $	$ 19,138	$ 19,138	$ 101,396
Threshold number of homes below a minimum threshold of profitability	10	10
Corporate and unallocated
Real Estate Properties [Line Items]
Number of Communities on Watch List	0	0	0
Number of Communities	0	0	0
Pre-analysis Book Value (BV) | $	$ 3,337	$ 3,337	$ 3,899
West
Real Estate Properties [Line Items]
Number of Communities on Watch List	4	4	9
Number of Communities	2	2	6
Pre-analysis Book Value (BV) | $	$ 15,801	$ 15,801	$ 75,028
Aggregate Undiscounted Cash Flow as a % of BV	94.40%	94.40%	114.00%
East
Real Estate Properties [Line Items]
Number of Communities on Watch List			4
Number of Communities			1
Pre-analysis Book Value (BV) | $			$ 22,469
Aggregate Undiscounted Cash Flow as a % of BV			88.50%
Southeast
Real Estate Properties [Line Items]
Number of Communities on Watch List	2	2	1
Number of Communities	0	0	0
Pre-analysis Book Value (BV) | $	$ 0	$ 0	$ 0
Aggregate Undiscounted Cash Flow as a % of BV	0.00%	0.00%	0.00%