Notes Payable - Terms (Details) - Home Building Consolidated $ in Millions	12 Months Ended
Sep. 30, 2023 USD ($)
SeniorNoteFortyTwo [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Oct. 15, 2024
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	2.70%
Senior notes, stated interest rate	2.50%
SeniorNoteFortyFour
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Oct. 15, 2025
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	2.80%
Senior notes, stated interest rate	2.60%
SeniorNoteFortySIx
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 600
Debt Instrument, Maturity Date	Oct. 15, 2026
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	1.50%
Senior notes, stated interest rate	1.30%
Senior Note Forty Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Oct. 15, 2027
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	1.60%
Senior notes, stated interest rate	1.40%
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%

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