REVENUE RECOGNITION - Major Good or Service (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues
Lease revenue	$ 12,933,000	$ 10,261,000	$ 35,409,000	$ 31,361,000
Lease Incentive Amortization	43,000	(76,000)	130,000	(227,000)
Commercial Loan and Master Lease Investments	413,000	855,000	2,300,000	908,000
Revenue from contract with customer, including assessed tax	544,000	214,000	631,000	709,000
Total Revenues	14,571,974	11,329,979	40,420,149	32,978,129
Lease Revenue - Base Rent
Revenues
Lease revenue	9,610,000	8,829,000	27,630,000	26,724,000
Lease Revenue - CAM
Revenues
Lease revenue	866,000	277,000	2,452,000	1,092,000
Lease Revenue - Reimbursements
Revenues
Lease revenue	1,432,000	508,000	2,918,000	1,597,000
Lease Revenue - Billboards
Revenues
Lease revenue	43,000	62,000	170,000	191,000
Above / Below Market Lease Accretion
Revenues
Lease revenue	433,000	607,000	1,352,000	1,811,000
Contributed Leased Assets Accretion
Revenues
Lease revenue		49,000		173,000
Management Services
Revenues
Total Revenues	682,000		2,080,000
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		186,000		598,000
Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	544,000	10,000	627,000	39,000
Fill Dirt and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax		18,000	6,000	72,000
Interest and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	506,000	23,000	757,000	72,000
Income Properties
Revenues
Lease Incentive Amortization	43,000	(76,000)	130,000	(227,000)
Total Revenues	12,933,029	10,260,831	35,409,172	31,360,544
Income Properties | Lease Revenue - Base Rent
Revenues
Lease revenue	9,610,000	8,811,000	27,630,000	26,652,000
Income Properties | Lease Revenue - CAM
Revenues
Lease revenue	866,000	277,000	2,452,000	1,092,000
Income Properties | Lease Revenue - Reimbursements
Revenues
Lease revenue	1,432,000	508,000	2,918,000	1,597,000
Income Properties | Lease Revenue - Billboards
Revenues
Lease revenue	43,000	62,000	170,000	191,000
Income Properties | Above / Below Market Lease Accretion
Revenues
Lease revenue	433,000	607,000	1,352,000	1,811,000
Income Properties | Contributed Leased Assets Accretion
Revenues
Lease revenue		49,000		173,000
Income Properties | Interest and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	506,000	23,000	757,000	72,000
Management Services
Revenues
Total Revenues	682,153		2,079,805
Management Services | Management Services
Revenues
Total Revenues	682,000		2,080,000
Interest Income from Commercial Loan and Master Lease Investments
Revenues
Commercial Loan and Master Lease Investments	413,000	855,000	2,300,000	908,000
Total Revenues	413,092	855,559	2,300,331	908,324
Real Estate Operations
Revenues
Total Revenues	543,700	213,589	630,841	709,261
Real Estate Operations | Lease Revenue - Base Rent
Revenues
Lease revenue		18,000		72,000
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		186,000		598,000
Real Estate Operations | Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	$ 544,000	$ 10,000	$ 627,000	$ 39,000