Inventory - Inventory Impairments and Abandonment Charges, by Reportable Segment (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Real Estate Properties [Line Items]
Impairment charges on land held for sale	$ 0	$ 1,257,000	$ 0	$ 1,257,000
Abandonment charges	231,000	1,009,000	696,000	1,009,000
Total impairment and abandonment charges	231,000	2,266,000	696,000	2,266,000
Corporate and unallocated
Real Estate Properties [Line Items]
Impairment charges on land held for sale	0	1,160,000	0	1,160,000
West Segment | Operating Segments
Real Estate Properties [Line Items]
Impairment charges on land held for sale	0	89,000	0	89,000
Abandonment charges	0	452,000	0	452,000
East Segment | Operating Segments
Real Estate Properties [Line Items]
Abandonment charges	0	32,000	465,000	32,000
Southeast Segment | Operating Segments
Real Estate Properties [Line Items]
Impairment charges on land held for sale	0	8,000	0	8,000
Abandonment charges	$ 231,000	$ 525,000	$ 231,000	$ 525,000