REVENUE RECOGNITION - Major Good or Service (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Lease revenue	$ 11,003,000	$ 10,724,000
Lease Incentive Amortization		(76,000)
Commercial Loan Investments	1,052,000
Revenue from contract with customer, including assessed tax	81,000	235,000
Interest and Other Revenue	117,000
Total Revenues	12,838,432	10,959,319
Lease Revenue - Base Rent
Revenues
Lease revenue	8,751,000	8,902,000
Lease Revenue - CAM
Revenues
Lease revenue	784,000	670,000
Lease Revenue - Reimbursements
Revenues
Lease revenue	790,000	546,000
Lease Revenue - Billboards
Revenues
Lease revenue	44,000	36,000
Above / Below Market Lease Accretion
Revenues
Lease revenue	474,000	581,000
Contributed Leased Assets Accretion
Revenues
Lease revenue	43,000	62,000
Management Fee Income
Revenues
Total Revenues	702,000
Mitigation Credit Sales
Revenues
Revenue from contract with customer, including assessed tax	4,000
Subsurface Lease Revenue
Revenues
Revenue from contract with customer, including assessed tax		199,000
Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	77,000	9,000
Fill Dirt and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax		27,000
Interest and Other Revenue
Revenues
Interest and Other Revenue		30,000
Income Properties
Revenues
Lease Incentive Amortization		(76,000)
Interest and Other Revenue	117,000
Total Revenues	11,003,031	10,724,418
Income Properties | Lease Revenue - Base Rent
Revenues
Lease revenue	8,751,000	8,875,000
Income Properties | Lease Revenue - CAM
Revenues
Lease revenue	784,000	670,000
Income Properties | Lease Revenue - Reimbursements
Revenues
Lease revenue	790,000	546,000
Income Properties | Lease Revenue - Billboards
Revenues
Lease revenue	44,000	36,000
Income Properties | Above / Below Market Lease Accretion
Revenues
Lease revenue	474,000	581,000
Income Properties | Contributed Leased Assets Accretion
Revenues
Lease revenue	43,000	62,000
Income Properties | Interest and Other Revenue
Revenues
Interest and Other Revenue		30,000
Management Fee Income
Revenues
Total Revenues	702,601
Management Fee Income | Management Fee Income
Revenues
Total Revenues	702,000
Interest Income from Commercial Loan Investments
Revenues
Commercial Loan Investments	1,052,000
Total Revenues	1,052,049
Real Estate Operations
Revenues
Total Revenues	80,751	234,901
Real Estate Operations | Lease Revenue - Base Rent
Revenues
Lease revenue		27,000
Real Estate Operations | Mitigation Credit Sales
Revenues
Revenue from contract with customer, including assessed tax	4,000
Real Estate Operations | Subsurface Lease Revenue
Revenues
Revenue from contract with customer, including assessed tax		199,000
Real Estate Operations | Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	$ 77,000	$ 9,000