Inventory - Narrative (Details) $ in Millions	3 Months Ended
	Dec. 31, 2016 USD ($) home Community	Dec. 31, 2015 Community	Sep. 30, 2016 USD ($) home
Real Estate [Abstract]
Number of substantially completed homes unsold | home	162		178
Total value of substantially completed homes | $	$ 47.1		$ 56.1
Threshold number of homes below a minimum threshold of profitability | home	10
Real Estate Properties [Line Items]
Number of communities on watch list	8	0
West Segment
Real Estate Properties [Line Items]
Number of communities on watch list	7
East Segment
Real Estate Properties [Line Items]
Number of communities on watch list	1