Summary of Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) tenant	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impairment of real estate			$ 0
Allowance for doubtful accounts	$ 339,000		339,000		$ 161,000
Rental revenue adjustment	55,000	$ 5,000	186,000	$ 124,000
Rental revenue adjustment due to COVID-19	$ 21,000		$ 55,000
Base rent, percentage received	93.00%		93.00%
Straight-line rent reserve adjustments due to COVID-19			$ 50,000
Number of tenants | tenant			4
Uncertain tax position to be recognized based on maximum cumulative probability percentage			50.00%
Operating loss carry-forwards	$ 345,000		$ 345,000
Deferred tax liabilities	95,000	96,000	95,000	96,000
Total lease liabilities	11,000		11,000		7,000
Operating lease payments	$ 11,000		$ 11,000
Operating lease, weighted average discount rate, percent	4.50%		4.50%
Operating lease right of use assets	$ 11,000		$ 11,000		$ 7
Rental revenues	2,140,000	3,250,000	6,662,000	9,769,000
Recoveries	$ 268,000	$ 609,000	$ 882,000	$ 1,859,000
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total lease liabilities						$ 21,000
Operating lease payments						$ 22,000
Operating lease, weighted average discount rate, percent						4.50%
Operating lease right of use assets						$ 21,000
Building and Building Improvements [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives			5 years
Building and Building Improvements [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Estimated useful lives			39 years