Inventory - Narrative (Details) $ in Thousands	3 Months Ended
	Dec. 31, 2018 USD ($) home Community	Dec. 31, 2017 USD ($) Community	Sep. 30, 2018 USD ($) home
Inventory Disclosure [Abstract]
Number of substantially completed homes unsold | home	223		240
Total value of substantially completed homes | $	$ 83,900		$ 84,800
Threshold number of homes below a minimum threshold of profitability | home	10
Inventory impairment charge | $	$ 1,007	$ 500
Real Estate Properties [Line Items]
Number of communities on watch list	4	2
Number of communities requiring further analysis	1	0
West Segment
Real Estate Properties [Line Items]
Number of communities on watch list	3
Number of communities requiring further analysis	0
Southeast Segment
Real Estate Properties [Line Items]
Number of communities on watch list	1
Number of communities requiring further analysis	1