Income Taxes, Continuing Operations - Deferred Tax Assets and Liabilities (Detail) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Gross deferred tax liabilities:
Property having a financial statement basis in excess of tax basis	$ 361,000	$ 361,000
Accounts receivable	238,000	213,000
Deferred income - conversion to cash basis of accounting for tax purposes	33,000	38,000
Insurance premiums and accrued leasing revenues	30,000	23,000
Gross deferred tax liabilities	662,000	635,000
Gross deferred tax assets:
Allowance for doubtful accounts	(231,000)	(206,000)
Prepaid rent	(51,000)	(23,000)
Accounts payable and accrued expenses	(65,000)	(69,000)
Accrued property taxes	(85,000)	(75,000)
Gross deferred tax assets	(432,000)	(373,000)
Deferred tax liabilities, net of deferred tax assets	$ 230,000	$ 262,000