Quarterly report pursuant to Section 13 or 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)

v3.5.0.2
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)
$ in Thousands
Sep. 30, 2016
USD ($)
partnership
property
Dec. 31, 2015
USD ($)
property
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Debt issuance costs reclassed from assets to liabilities following adoption of ASU 2015-03 $ 2,911 $ 1,923
Variable Interest Entity [Line Items]    
Number of properties held for sale | property 3 0
Number of self storage properties owned by VIEs | property 352  
Net book value of real estate owned by consolidated VIEs $ 1,521,021 $ 1,079,101
Carrying value of fixed rate mortgages held by VIEs 716,587 564,886
Mortgages [Member] | Fixed Rate Mortgages [Member]    
Variable Interest Entity [Line Items]    
Carrying value of fixed rate mortgages held by VIEs $ 206,087 176,911
Variable Interest Entity, Primary Beneficiary [Member]    
Variable Interest Entity [Line Items]    
Number of partnerships considered variable interest entities | partnership 21  
Number of self storage properties owned by VIEs | property 34  
Net book value of real estate owned by consolidated VIEs $ 258,000 262,600
Variable Interest Entity, Primary Beneficiary [Member] | Mortgages [Member] | Fixed Rate Mortgages [Member]    
Variable Interest Entity [Line Items]    
Carrying value of fixed rate mortgages held by VIEs 41,900 43,200
Accounting Standards Updated 2015-03 [Member] | Assets [Member]    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Debt issuance costs reclassed from assets to liabilities following adoption of ASU 2015-03 (5,400) (2,800)
Accounting Standards Updated 2015-03 [Member] | Debt Financing [Member]    
New Accounting Pronouncements or Change in Accounting Principle [Line Items]    
Debt issuance costs reclassed from assets to liabilities following adoption of ASU 2015-03 $ 5,400 $ 2,800