INVESTMENT IN UNCONSOLIDATED JOINT VENTURES (Investments in Unconsolidated Joint Ventures) (Details) $ in Thousands	Mar. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($)
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 47,373	$ 44,869
NIP Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of Properties \| property	2
Investment Balance	$ 1,476	1,476
NIP Joint Venture \| Maximum
Schedule of Equity Method Investments [Line Items]
Ownership %	5.00%
110 William Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of Properties \| property	1
Ownership %	60.00%
Investment Balance	$ 0	325
353 Sacramento Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of Properties \| property	1
Ownership %	55.00%
Investment Balance	$ 42,905	43,068
Battery Point Series A-3 Preferred Units
Schedule of Equity Method Investments [Line Items]
Investment Balance	$ 2,992	$ 0

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

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- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

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- Definition

The carrying amount of investments in unconsolidated real estate and other joint ventures not separately presented. This includes direct and indirect investments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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