Income Taxes, Continuing Operations - Deferred Tax Assets and Liabilities (Detail) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Gross deferred tax liabilities:
Property having a financial statement basis in excess of tax basis	$ 364,000	$ 361,000
Accounts receivable	306,000	289,000
Deferred income - conversion to cash basis of accounting for tax purposes	14,000	19,000
Insurance premiums	39,000	50,000
Gross deferred tax liabilities	723,000	719,000
Gross deferred tax assets:
Allowance for doubtful accounts	(288,000)	(279,000)
Prepaid rent	(45,000)	(25,000)
Accounts payable and accrued expenses	(60,000)	(74,000)
Accrued property taxes	(82,000)	(70,000)
Gross deferred tax assets	(475,000)	(448,000)
Deferred tax liabilities, net of deferred tax assets	$ 248,000	$ 271,000