Description of leasing arrangements and subsequent event - Company's Revenue from Major Tenants (Detail) - Major Customers [Member] - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Entity-Wide Revenue	$ 3,790,000	$ 3,412,000
Lamar Outdoor Advertising, LLC [Member]
Segment Reporting Information [Line Items]
Entity-Wide Revenue	1,231,000	1,255,000
Metropark Ltd [Member]
Segment Reporting Information [Line Items]
Entity-Wide Revenue	726,000	411,000
HGIT Center Place [Member]
Segment Reporting Information [Line Items]
Entity-Wide Revenue	641,000	625,000
1701 R.C. Sarasota Invest, LLC [Member]
Segment Reporting Information [Line Items]
Entity-Wide Revenue	618,000	618,000
Waterplace Condominiums [Member]
Segment Reporting Information [Line Items]
Entity-Wide Revenue	$ 574,000	$ 503,000