Quarterly report pursuant to Section 13 or 15(d)

ORGANIZATION AND NATURE OF OPERATIONS (Details)

v3.5.0.2
ORGANIZATION AND NATURE OF OPERATIONS (Details)
$ / shares in Units, storage_unit in Thousands, $ in Thousands, ft² in Millions
 1 Months Ended 6 Months Ended
Jul. 06, 2016
USD ($)
$ / shares
shares
Apr. 28, 2015
USD ($)
$ / shares
shares
Aug. 09, 2016
USD ($)
Jun. 30, 2016
USD ($)
ft²
storage_unit
state
property
$ / shares
shares
Jun. 30, 2015
USD ($)
Dec. 31, 2015
$ / shares
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Common shares of beneficial interest, par value (in dollars per share) | $ / shares       $ 0.01   $ 0.01
Net proceeds from issuance of common shares in IPO | $       $ 0 $ 278,070  
Number of self storage properties owned | property       318    
Number of states that self storage properties are owned in | state       18    
Total rentable square feet in self storage properties | ft²       18.7    
Number of storage units owned | storage_unit       149    
OP units [Member] | NSA OP, LP [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Number of common shares offered (in shares) | shares       3,372,531    
Common Shares [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Common shares of beneficial interest, par value (in dollars per share) | $ / shares       $ 0.01    
Net proceeds from issuance of common shares in IPO | $   $ 278,100        
Common Shares [Member] | IPO [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Number of common shares offered (in shares) | shares   23,000,000        
Public offering share price (in dollars per share) | $ / shares   $ 13.00        
Common Shares [Member] | Over-Allotment Option [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Number of common shares offered (in shares) | shares   3,000,000        
Subsequent Event [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Proceeds from issuance of common shares | $ $ 237,700   $ 237,700      
Subsequent Event [Member] | Common Shares [Member] | Over-Allotment Option [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Number of common shares offered (in shares) | shares 1,571,250          
Public offering share price (in dollars per share) | $ / shares $ 20.75          
Subsequent Event [Member] | Common Shares [Member] | Follow On Offering [Member]            
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]            
Number of common shares offered (in shares) | shares 12,046,250          
Public offering share price (in dollars per share) | $ / shares $ 20.75