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

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
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