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SIGNIFICANT ACCOUNTING POLICIES (Details)	1 Months Ended	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) state item property	Dec. 31, 2020 USD ($) state item	Sep. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) item tenant state	Dec. 31, 2019 USD ($) tenant	Dec. 31, 2018 USD ($) tenant
Investment in Joint Ventures and Variable Interest Entities
Number of Unconsolidated Joint Venture VIEs | item	0	0								0
Recourse debt of joint ventures	$ 0	$ 0								$ 0
Impairment charges										0
Revenue Recognition
Revenue		18,732,000	$ 21,071,000	$ 20,861,000	$ 21,239,000	$ 22,448,000	$ 20,414,000	$ 20,719,000	$ 21,155,000	81,903,000	$ 84,736,000	$ 79,126,000
Escrows
Real estate taxes, insurance and other escrows	859,000	859,000				934,000				859,000	934,000
Depreciation and Amortization
Depreciation and amortization										22,964,000	22,026,000	24,155,000
Deferred Financing Costs
Accumulated amortization of deferred financing costs	$ 4,599,000	$ 4,599,000				$ 3,799,000				$ 4,599,000	$ 3,799,000
Concentration of Credit Risk
Number of states in which properties are located | state	31	31								31
Segment Reporting
Number of operating segments | item										1
Collectability of Lease Payments
Bad debt expense												$ 684,000
Real Estate in Houston, TX
New Accounting Pronouncements
Number of properties sold | property	2
Seller-financing provided by the Company	$ 4,612,500	$ 4,612,500								$ 4,612,500
Term of loan	1 year
Percentage of seller-financing provided by the Company	50.00%	50.00%								50.00%
Total Revenue | Geographic concentration
Concentration of Credit Risk
Number of states in which properties are located | state	31	31								31
Total Revenue | Customer concentration
Concentration of Credit Risk
Number of tenants contributed over 10% of total revenues | tenant										0	0	0
Buildings
Depreciation and Amortization
Estimated useful life										40 years
Above and Below Market Leases | Minimum
Purchase Accounting for Acquisition of Real Estate
Useful Life										1 year
Above and Below Market Leases | Maximum
Purchase Accounting for Acquisition of Real Estate
Useful Life										35 years
Tenant reimbursements
Revenue Recognition
Revenue										$ 10,512,000	$ 10,443,000	$ 8,456,000

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