MORTGAGE LOANS AND NOTES PAYABLE - Summary (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Mortgage loans and Notes payable
Less: Loan procurement costs, net	$ (2,475)	$ (2,800)
Total mortgage loans and notes payable	138,716	111,455
Net book value of self-storage facilities	3,208,439	2,872,983
Mortgages
Mortgage loans and Notes payable
Carrying value	135,186	109,993
Plus: Unamortized fair value adjustment	4,375	2,219
Less: Loan procurement costs, net	(845)	(757)
Total mortgage loans and notes payable	138,716	111,455
Net book value of self-storage facilities	$ 244,800	195,400
YSI 59
Mortgage loans and Notes payable
Carrying value		9,012
Effective interest rate (as a percent)	4.82%
YSI 60
Mortgage loans and Notes payable
Carrying value		3,546
Effective interest rate (as a percent)	5.04%
YSI 51
Mortgage loans and Notes payable
Carrying value	$ 6,921	6,984
Effective interest rate (as a percent)	5.15%
YSI 64
Mortgage loans and Notes payable
Carrying value	$ 7,710	7,781
Effective interest rate (as a percent)	3.54%
YSI 62
Mortgage loans and Notes payable
Carrying value	$ 7,769	7,835
Effective interest rate (as a percent)	3.54%
YSI 67
Mortgage loans and Notes payable
Carrying value	$ 6,291
Effective interest rate (as a percent)	2.55%
YSI 33
Mortgage loans and Notes payable
Carrying value	$ 10,009	10,154
Effective interest rate (as a percent)	6.42%
YSI 26
Mortgage loans and Notes payable
Carrying value	$ 8,515	8,606
Effective interest rate (as a percent)	4.56%
YSI 57
Mortgage loans and Notes payable
Carrying value	$ 2,989	3,021
Effective interest rate (as a percent)	4.61%
YSI 55
Mortgage loans and Notes payable
Carrying value	$ 23,163	23,369
Effective interest rate (as a percent)	4.85%
YSI 24
Mortgage loans and Notes payable
Carrying value	$ 26,830	27,185
Effective interest rate (as a percent)	4.64%
YSI 65
Mortgage loans and Notes payable
Carrying value	$ 2,479	$ 2,500
Effective interest rate (as a percent)	3.85%
YSI 66
Mortgage loans and Notes payable
Carrying value	$ 32,510
Effective interest rate (as a percent)	3.51%

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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