Inventory - Recoverability Schedule of Inventory assets Held for Development, by Reportable Segment (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2016 USD ($) Community	Sep. 30, 2015 Community	Sep. 30, 2014 USD ($) Community
Real Estate Properties [Line Items]
Number of Communities on Watch List	14		8
Number of Communities	7	0	4
Pre-analysis Book Value (BV) | $	$ 101,396		$ 35,228
Corporate and unallocated
Real Estate Properties [Line Items]
Number of Communities on Watch List	0		0
Number of Communities	0		0
Pre-analysis Book Value (BV) | $	$ 3,899		$ 2,558
West
Real Estate Properties [Line Items]
Number of Communities on Watch List	9		5
Number of Communities	6		3
Pre-analysis Book Value (BV) | $	$ 75,028		$ 25,191
Aggregate Undiscounted Cash Flow as a % of BV	114.00%		90.90%
East
Real Estate Properties [Line Items]
Number of Communities on Watch List	4		1
Number of Communities	1		0
Pre-analysis Book Value (BV) | $	$ 22,469		$ 0
Aggregate Undiscounted Cash Flow as a % of BV	88.50%		0.00%
Southeast
Real Estate Properties [Line Items]
Number of Communities on Watch List	1		2
Number of Communities	0		1
Pre-analysis Book Value (BV) | $	$ 0		$ 7,479
Aggregate Undiscounted Cash Flow as a % of BV	0.00%		120.20%