Inventory - Narrative (Details) $ in Millions	3 Months Ended
	Dec. 31, 2017 USD ($) home lot Community	Sep. 30, 2017 USD ($) home	Dec. 31, 2016 Community
Inventory Disclosure [Abstract]
Number of substantially completed homes unsold | home	167	171
Total value of substantially completed homes | $	$ 54.3	$ 52.6
Threshold number of homes below a minimum threshold of profitability | home	10
Real Estate Properties [Line Items]
Assets acquired from Bill Clark Homes | lot	450
Payments to Acquire Real Estate | $	$ 29.0
Number of communities on watch list	2		8
Number of communities requiring further analysis	0		0
West Segment
Real Estate Properties [Line Items]
Number of communities requiring further analysis	1		7
East Segment
Real Estate Properties [Line Items]
Number of communities requiring further analysis			1
Southeast Segment
Real Estate Properties [Line Items]
Number of communities requiring further analysis	1
Raleigh
Real Estate Properties [Line Items]
Communities acquired from Bill Clark Homes	4
Myrtle Beach
Real Estate Properties [Line Items]
Communities acquired from Bill Clark Homes	3