Inventory - Recoverability Schedule of Inventory assets Held for Development, by Reportable Segment (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2018 USD ($) home Community	Sep. 30, 2018 USD ($) lot Community	Sep. 30, 2017 USD ($) Community
Real Estate Properties [Line Items]
Number of Communities on Watch List	4	4	6
Number of Communities	2	2	2
Pre-analysis Book Value (BV) | $	$ 5,667	$ 5,667	$ 19,138
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) | $	$ 1,307	$ 1,307	$ 3,337
West
Real Estate Properties [Line Items]
Number of Communities on Watch List	2	2	4
Number of Communities	0	0	2
Pre-analysis Book Value (BV) | $	$ 0	$ 0	$ 15,801
Aggregate Undiscounted Cash Flow as a % of BV	0.00%	0.00%	94.40%
Southeast
Real Estate Properties [Line Items]
Number of Communities on Watch List	2	2	2
Number of Communities	2	2	0
Pre-analysis Book Value (BV) | $	$ 4,360	$ 4,360	$ 0
Aggregate Undiscounted Cash Flow as a % of BV	99.00%	99.00%	0.00%