Summary of Significant Accounting Policies - Business Acquisition (Details) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2023 USD ($) lot	Dec. 31, 2022 USD ($) lot	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired			$ 212.9	$ 271.5	$ 24.5
Scehdule of Business Information [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired			$ 212.9	$ 271.5	$ 24.5
Riggins Custom Homes
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired		$ 107.0
Scehdule of Business Information [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired		$ 107.0
Business Acquisition, Number of Homes Acquired | lot		170
Business Acquisition, Number of Lots Acquired | lot		3,000
Truland Homes
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payments to Acquire Businesses, Net of Cash Acquired	$ 110.0
Scehdule of Business Information [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 110.0
Business Acquisition, Number of Homes Acquired | lot	155
Business Acquisition, Number of Lots Acquired | lot	620
Business Acquisition, Number of Controlled Lots Acquired through Land Purchase Contracts | lot	660