Income Taxes - Text (Detail) - USD ($)			9 Months Ended	12 Months Ended
	Sep. 30, 2020	Oct. 05, 2017	Sep. 30, 2018	Sep. 30, 2020	Sep. 30, 2019
Operating Loss Carryforwards [Line Items]
Federal statutory rate			21.00%	21.00%	21.00%
Net operating loss carryforwards	$ 1,700,000			$ 1,700,000	$ 15,100,000
Deferred Tax Assets, Valuation Allowance	(1,500,000)			(1,500,000)	(3,300,000)
Unrecognized Tax Benefits, Interest on Income Taxes Expense			$ 0	0	0
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	0		$ 0	0	0
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount				2,300,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	0			0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	1,700,000			1,700,000
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	1,400,000			1,400,000
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	$ 300,000			300,000
D.R. Horton, Inc. [Member] | Reimbursement From Parent [Member]
Operating Loss Carryforwards [Line Items]
Related Party Transaction, Amounts of Transaction					$ 400,000
D.R. Horton, Inc. [Member] | Reimbursement To Parent [Member]
Operating Loss Carryforwards [Line Items]
Related Party Transaction, Amounts of Transaction				$ 200,000
Majority Shareholder [Member] | D.R. Horton, Inc. [Member]
Operating Loss Carryforwards [Line Items]
Sale of Stock, Percentage of Ownership after Transaction	65.00%	75.00%