SELF STORAGE PROPERTY ACQUISITIONS - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Business Combination, Pro Forma Information [Line Items]
Pro forma revenue	$ 32,611	$ 20,070	$ 63,809	$ 37,034
Pro forma net income (loss)	$ 1,814	$ (6,365)	$ 822	$ (11,289)
Earnings (loss) per share (basic) (in dollars per share)	$ 0.22	$ 0.00	$ 0.44	$ 0.00
Pro forma earnings (loss) per share (basic) (in dollars per share)	0.22	0.00	0.44	0.00
Earnings (loss) per share (diluted) (in dollars per share)	0.00	0.00	0.00	0.00
Pro forma earnings (loss) per share (diluted) (in dollars per share)	$ 0.03	$ 0.00	$ 0.03	$ 0.00
Pro forma net income (loss)	$ 719	$ 5,089	$ 1,318	$ 5,271
April - May 2015 Acquisitions [Member]
Business Combination, Pro Forma Information [Line Items]
Pro forma revenue	961	2,629	3,782	5,215
Pro forma net income (loss)	1,404	(55)	2,292	(1,337)
January 2015 Acquisitions [Member]
Business Combination, Pro Forma Information [Line Items]
Pro forma revenue	0	1,226	86	2,443
Pro forma net income (loss)	317	(152)	1,208	(991)
Consolidated Entities Excluding Acquirees [Member]
Business Combination, Pro Forma Information [Line Items]
Pro forma revenue	31,650	16,215	59,941	29,376
Pro forma net income (loss)	$ 93	$ (6,158)	$ (2,678)	$ (8,961)
Credit Facility [Member] \| Line of Credit [Member] \| Revolving line of credit [Member]
Business Combination, Pro Forma Information [Line Items]
Effective interest rate	1.79%		1.79%

[Line Items] for Business Combination, Pro Forma Information [Table]

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The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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