Owned Inventory - Narrative (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2023 USD ($) home	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) home	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($) home
Inventory Disclosure [Abstract]
Number of homes under construction | home	2,340		2,340		2,688
Number of homes under construction, spec homes | home	720		720		887
Total, spec homes	$ 212,700,000		$ 212,700,000		$ 246,500,000
Number of homes under construction, in-process spec homes | home	592		592		793
In-process spec homes	$ 159,700,000		$ 159,700,000		$ 208,700,000
Number of homes under construction, finished spec homes | home	128		128		94
Finished spec homes	$ 53,000,000		$ 53,000,000		$ 37,800,000
Threshold number of homes below a minimum threshold of profitability | home			10
Impairment of projects in process	0	$ 0	$ 0	$ 0
Total impairment charges on land held for sale	0	0	0	440,000
Fair value of impaired long-lived assets to be disposed of		300,000		300,000
Total abandonments charges	$ 315,000	$ 0	$ 616,000	$ 495,000