Owned Inventory - Narrative (Details)	12 Months Ended
	Sep. 30, 2023 USD ($) home	Sep. 30, 2022 USD ($) home community	Sep. 30, 2021 USD ($)
Segment Reporting Information [Line Items]
Number of homes under construction | home	2,163	2,688
Number of homes under construction, spec homes | home	779	887
Total, spec homes	$ 218,000,000	$ 246,500,000
Number of homes under construction, in-process spec homes | home	645	793
In-process spec homes	$ 162,000,000	$ 208,700,000
Number of homes under construction, finished spec homes | home	134	94
Finished spec homes	$ 56,000,000	$ 37,800,000
Threshold number of homes below a minimum threshold of profitability | home	10
Impairment of projects in process	$ 0	0	$ 0
Land held for sale	0	1,868,000	0
Fair value of impaired long-lived assets to be disposed of		900,000
Abandonments	$ 641,000	$ 1,095,000	$ 853,000
West
Segment Reporting Information [Line Items]
Number of communities | community		2