Notes Payable - Terms (Details) - Home Building Consolidated $ in Millions	12 Months Ended
Sep. 30, 2025 USD ($)
1.3% Senior Notes due 2026 [Member]
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%
1.4% Senior Notes due 2027 [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%
4.85% Senior Notes due 2030
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 500
Debt Instrument, Maturity Date	Oct. 15, 2030
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	5.10%
Senior notes, stated interest rate	4.85%
5.0% Senior Notes due 2034 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 700
Debt Instrument, Maturity Date	Oct. 15, 2034
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	5.20%
Senior notes, stated interest rate	5.00%
5.5% Senior Notes due 2035
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 700
Debt Instrument, Maturity Date	Oct. 15, 2035
Debt Instrument, Call Feature	Yes
Debt Instrument, Interest Rate, Effective Percentage	5.60%
Senior notes, stated interest rate	5.50%
Senior Notes [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%

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