REVENUE RECOGNITION - Major Good or Service (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues
Lease revenue	$ 11,473,000	$ 10,375,000	$ 22,476,000	$ 21,099,000
Lease Incentive Amortization	43,000	(76,000)	87,000	(151,000)
Commercial Loan Investments	835,000	53,000	1,887,000	53,000
Revenue from contract with customer, including assessed tax	6,000	261,000	87,000	496,000
Total Revenues	13,009,743	10,688,831	25,848,175	21,648,150
Lease Revenue - Base Rent
Revenues
Lease revenue	9,271,000	8,667,000	18,021,000	17,569,000
Lease Revenue - CAM
Revenues
Lease revenue	856,000	471,000	1,586,000	1,141,000
Lease Revenue - Reimbursements
Revenues
Lease revenue	612,000	543,000	1,486,000	1,088,000
Lease Revenue - Billboards
Revenues
Lease revenue	83,000	93,000	127,000	129,000
Above / Below Market Lease Accretion
Revenues
Lease revenue	444,000	623,000	918,000	1,204,000
Contributed Leased Assets Accretion
Revenues
Lease revenue		62,000		124,000
Management Services
Revenues
Total Revenues	695,000		1,398,000
Mitigation Credit Sales
Revenues
Revenue from contract with customer, including assessed tax			4,000
Subsurface Lease Revenue
Revenues
Commercial Loan Investments	835,000
Revenue from contract with customer, including assessed tax		214,000		413,000
Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	6,000	20,000	83,000	29,000
Fill Dirt and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	5,000	27,000	5,000	54,000
Interest and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	164,000	19,000	251,000	49,000
Income Properties
Revenues
Lease Incentive Amortization	43,000	(76,000)	87,000	(151,000)
Total Revenues	11,473,112	10,375,295	22,476,143	21,099,713
Income Properties | Lease Revenue - Base Rent
Revenues
Lease revenue	9,271,000	8,640,000	18,021,000	17,515,000
Income Properties | Lease Revenue - CAM
Revenues
Lease revenue	856,000	471,000	1,586,000	1,141,000
Income Properties | Lease Revenue - Reimbursements
Revenues
Lease revenue	612,000	543,000	1,486,000	1,088,000
Income Properties | Lease Revenue - Billboards
Revenues
Lease revenue	83,000	93,000	127,000	129,000
Income Properties | Above / Below Market Lease Accretion
Revenues
Lease revenue	444,000	623,000	918,000	1,204,000
Income Properties | Contributed Leased Assets Accretion
Revenues
Lease revenue		62,000		124,000
Income Properties | Interest and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	164,000	19,000	251,000	49,000
Management Services
Revenues
Total Revenues	695,051		1,397,652
Management Services | Management Services
Revenues
Total Revenues	695,000		1,398,000
Interest Income from Commercial Loan Investments
Revenues
Commercial Loan Investments	835,000	53,000	1,887,000	53,000
Total Revenues	835,190	52,765	1,887,239	52,765
Interest Income from Commercial Loan Investments | Subsurface Lease Revenue
Revenues
Commercial Loan Investments	835,000
Real Estate Operations
Revenues
Total Revenues	6,390	260,771	87,141	495,672
Real Estate Operations | Lease Revenue - Base Rent
Revenues
Lease revenue		27,000		54,000
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		214,000		413,000
Real Estate Operations | Subsurface Revenue - Other
Revenues
Revenue from contract with customer, including assessed tax	1,000	$ 20,000	78,000	$ 29,000
Real Estate Operations | Interest and Other Revenue
Revenues
Revenue from contract with customer, including assessed tax	$ 5,000		$ 5,000