SELF-STORAGE INVESTMENT PORTFOLIO (Real Estate Investment, Impact in Consolidated Statement of Operations, Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Investments [Line Items]
Rental and other property-related income from real estate owned	$ 805	$ 105	$ 1,428	$ 168
Real Estate Investment [Member]
Schedule of Investments [Line Items]
Rental and other property-related income from real estate owned	805	105	1,428	168
Property operating expenses of real estate owned	(420)	(43)	(731)	(74)
Depreciation and amortization expense	(887)	(38)	(1,589)	(62)
Total expenses of real estate owned	$ (1,307)	$ (81)	$ (2,320)	$ (136)

Amount of depreciation expense on real estate assets during the period.

No definition available.

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- Definition

It represents amount of property operating expenses of real estate owned.

+ References

No definition available.

+ Details

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- Definition

Generally recurring costs associated with normal operations except for the portion of these expenses which can be clearly related to production and included in cost of sales or services. Includes selling, general and administrative expense.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The aggregate revenue from real estate operations during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(e))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Balance Type:	credit
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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.

+ References

No definition available.

+ Details

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- Details

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