Income Taxes - Text (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 0.7	$ 0.9
Deferred Tax Assets, Valuation Allowance	(0.6)	(0.8)
Unrecognized Tax Benefits	0.0	0.0	$ 0.0
Corporate AMT credit carryforwards	16.5	0.0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0.7
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	0.3
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	0.4
D.R. Horton, Inc. [Member] | Reimbursement To Parent [Member]
Operating Loss Carryforwards [Line Items]
Related Party Transaction, Amounts of Transaction	$ 0.9	$ 2.2	$ 1.7