Owned Inventory - Narrative (Details)	12 Months Ended
	Sep. 30, 2022 USD ($) community home	Sep. 30, 2021 USD ($) home	Sep. 30, 2020 USD ($) community
Segment Reporting Information [Line Items]
Number of homes under construction | home	2,688	2,912
Number of homes under construction, spec homes | home	887	576
Total, spec homes	$ 246,500,000	$ 116,400,000
Number of homes under construction, in-process spec homes | home	793	542
In-process spec homes	$ 208,700,000	$ 105,200,000
Number of homes under construction, finished spec homes | home	94	34
Finished spec homes	$ 37,800,000	$ 11,200,000
Threshold number of homes below a minimum threshold of profitability | home	10
Impairment of projects in process	$ 0	0	$ 0
Land held for sale	1,900,000	0	$ 1,300,000
Number of communities | community			2
Abandonments	$ 1,095,000	$ 853,000	$ 1,646,000
West
Segment Reporting Information [Line Items]
Number of communities | community	2		1
Southeast
Segment Reporting Information [Line Items]
Number of communities | community			1