SIGNIFICANT ACCOUNTING POLICIES (Details)		12 Months Ended
	Jan. 03, 2012	Dec. 31, 2017 USD ($) item shares	Dec. 31, 2016 USD ($) tenant	Dec. 31, 2015 USD ($) tenant	Dec. 31, 2014 USD ($) tenant
Principles of Consolidation
Value at which partnership investments discontinue use of equity method		$ 0
Amount of legal obligations related to investments no longer classified as equity method		$ 0
Revenue Recognition
Period for which arrears are charged against income		60 days
Deferred Financing Costs
Amortization of deferred financing costs		$ 193,000	$ 188,000	$ 171,000
Income Taxes
Provision for income taxes		$ 0
Segment Reporting
Number of segments | item		1
Income Per Unit
Dilutive units | shares		0
Concentration of Credit Risks and Financial Instruments
Single tenants | tenant			0	0	0
Federally uninsured amounts of cash and cash equivalents, and security deposits included in prepaid expenses and other assets		$ 8,898,000	$ 8,911,000
Advertising Expense
Advertising expense		$ 201,040	191,815	$ 165,070
Interest Capitalized
Capitalized interest			0	0	$ 0
Amortization of deferred financing costs
Reclassification
Prior period adjustment				(171,000)
Interest expenses
Reclassification
Prior period adjustment				171,000
Net income
Reclassification
Prior period adjustment			$ 0	$ 0	$ 0
Minimum
Principles of Consolidation
Ownership interest in each subsidiary (as a percent)		99.67%
Interest Capitalized
Criteria of capitalization of interest on property based on specified period of construction		1 year
Minimum | Cash and cash equivalents
Concentration of Credit Risks and Financial Instruments
Interest rate on interest bearing accounts (as a percent)		0.01%
Maximum
Principles of Consolidation
Ownership interest in each subsidiary (as a percent)		100.00%
Maximum | Cash and cash equivalents
Concentration of Credit Risks and Financial Instruments
Interest rate on interest bearing accounts (as a percent)		0.20%
Investment Properties
Principles of Consolidation
Number of limited liability companies/partnerships | item		9
Investment Properties | Minimum
Principles of Consolidation
Percentage of ownership interest		40.00%
Investment Properties | Maximum
Principles of Consolidation
Percentage of ownership interest		50.00%
Class A
Income (Loss) Per Depositary Receipt
Forward split of depositary receipts	3
Exchange ratio of depositary receipts for partnership units before adjustment	10
Exchange ratio of depositary receipts for partnership units after adjustment	30
Number of units in each depository receipt	0.03333