Quarterly report pursuant to Section 13 or 15(d)

SUBSEQUENT EVENTS (Details)

v3.5.0.2
SUBSEQUENT EVENTS (Details)
$ / shares in Units, $ in Thousands
 1 Months Ended 3 Months Ended 6 Months Ended
Aug. 09, 2016
USD ($)
Jul. 06, 2016
USD ($)
$ / shares
shares
Apr. 28, 2015
shares
Aug. 09, 2016
USD ($)
property
shares
Jun. 30, 2016
USD ($)
property
Mar. 31, 2016
USD ($)
property
Jun. 30, 2015
property
Mar. 31, 2015
property
Jun. 30, 2016
USD ($)
property
Jun. 30, 2015
USD ($)
Subsequent Event [Line Items]                    
Number of self storage properties acquired | property         25 17 21 6 42  
Cash consideration for acquired self storage properties                 $ 123,932 $ 47,523
Consideration given, value of OP Equity         $ 80,986 $ 19,068     $ 100,054  
Subsequent Event [Member]                    
Subsequent Event [Line Items]                    
Proceeds from issuance of common shares   $ 237,700   $ 237,700            
Subsequent Event [Member] | Series of Individually Immaterial Business Acquisitions [Member]                    
Subsequent Event [Line Items]                    
Number of self storage properties acquired | property       26            
Aggregate purchase price of self storage properties acquired subsequent to period end       $ 167,600            
Cash consideration for acquired self storage properties       165,800            
Consideration given, value of OP Equity       $ 1,100            
Other working capital liabilities assumed $ 700                  
Subsequent Event [Member] | Series of Individually Immaterial Business Acquisitions [Member] | Participating Regional Operator [Member]                    
Subsequent Event [Line Items]                    
Number of self storage properties acquired | property       1            
Subsequent Event [Member] | Series of Individually Immaterial Business Acquisitions [Member] | Unidentified Third Parties [Member]                    
Subsequent Event [Line Items]                    
Number of self storage properties acquired | property       25            
OP units [Member] | Subsequent Event [Member] | Series of Individually Immaterial Business Acquisitions [Member]                    
Subsequent Event [Line Items]                    
Number of units issued for acquisitions | shares       49,230            
Follow On Offering [Member] | Common Shares [Member] | Subsequent Event [Member]                    
Subsequent Event [Line Items]                    
Number of common shares offered (in shares) | shares   12,046,250                
Public offering share price (in dollars per share) | $ / shares   $ 20.75                
Over-Allotment Option [Member] | Common Shares [Member]                    
Subsequent Event [Line Items]                    
Number of common shares offered (in shares) | shares     3,000,000              
Over-Allotment Option [Member] | Common Shares [Member] | Subsequent Event [Member]                    
Subsequent Event [Line Items]                    
Number of common shares offered (in shares) | shares   1,571,250                
Public offering share price (in dollars per share) | $ / shares   $ 20.75                
Due Diligence Costs [Member] | Management [Member] | Subsequent Event [Member] | Participating Regional Operator [Member]                    
Subsequent Event [Line Items]                    
Due diligence expenses payable to the PROs       $ 300