Annual report pursuant to Section 13 and 15(d)

Investment in Joint Ventures - Summary of Company's Unconsolidated Joint Ventures (Parenthetical) (Detail)

v3.10.0.1
Investment in Joint Ventures - Summary of Company's Unconsolidated Joint Ventures (Parenthetical) (Detail)
$ in Thousands
1 Months Ended 12 Months Ended
Jan. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Property
Dec. 31, 2017
USD ($)
Property
Dec. 31, 2016
USD ($)
Schedule of Equity Method Investments [Line Items]        
Number of storage facilities acquired | Property   8 2  
Payment for property acquisition   $ 72,603 $ 21,880 $ 1,750,267
Mortgages payable   12,302 12,674  
Distributions from unconsolidated joint ventures   8,561 7,055 5,207
Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   3,000    
Distributions from unconsolidated joint ventures   5,700    
Excess of investment over net asset due to capitalization of acquisition related costs   1,700    
Sovran HHF Storage Holdings II LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   400    
Distributions from unconsolidated joint ventures   2,000    
191 III Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   200    
Distributions from unconsolidated joint ventures   500    
Life Storage-SERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Distributions from unconsolidated joint ventures   200    
Iskalo Office Holdings, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Distributions from unconsolidated joint ventures   300    
Rent paid during the period   1,200 $ 1,200 $ 1,200
SNL/Orix 1200 McDonald Ave., LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   100    
Non-recourse mortgage loan principal outstanding   10,700    
SNL Orix Merrick, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   100    
Non-recourse mortgage loan principal outstanding   11,900    
Review Avenue Partners LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   400    
Non-recourse mortgage loan principal outstanding   $ 29,500    
Review Avenue Partners LLC [Member] | Subsequent Event [Member]        
Schedule of Equity Method Investments [Line Items]        
Payment for property acquisition $ 46,400      
Equity method investment ownership percentage acquired 60.00%      
Payments of transfer tax $ 700      
Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   12    
Contribution of company to joint venture as share in capital   $ 9,300    
Life Storage-HIERS Storage LLC [Member] | Storage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Payment for property acquisition   91,300    
Mortgages payable   45,400    
Contribution of company to joint venture as share in capital   9,100    
Urban Box Coralway Storage, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   500    
NYX Don Mills Storage LP [Member] | Common Stock Shares [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   1,000    
NYX Sheridan Storage LP [Member] | Common Stock Shares [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   700    
NYX Appleby Storage LP [Member] | Common Stock Shares [Member]        
Schedule of Equity Method Investments [Line Items]        
Contribution of company to joint venture as share in capital   $ 1,000    
Arizona [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   11    
Arizona [Member] | N 32nd Street Self Storage, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Non-recourse mortgage loan principal outstanding   $ 6,100    
Arizona [Member] | Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   2    
Colorado [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   4    
Florida [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   3    
Florida [Member] | Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Florida [Member] | Urban Box Coralway Storage, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Georgia [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Georgia [Member] | Life Storage-SERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   3    
Georgia [Member] | Life Storage-SERS Storage LLC [Member] | Storage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of storage facilities acquired | Property     3  
Payment for property acquisition     $ 39,100  
Mortgages payable     $ 22,000  
Kentucky [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   2    
Nevada [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   5    
New Jersey [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   2    
New Jersey [Member] | Sovran HHF Storage Holdings II LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   17    
Ohio [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   6    
Pennsylvania [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Pennsylvania [Member] | Sovran HHF Storage Holdings II LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   3    
Tennessee [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   2    
Texas [Member] | Sovran HHF Storage Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   20    
Texas [Member] | Sovran HHF Storage Holdings II LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   10    
Texas [Member] | Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   7    
Arizona, Nevada and Tennessee [Member] | Sovran HHF Storage Holdings LLC [Member] | Storage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of storage facilities acquired | Property     18  
Payment for property acquisition     $ 330,000  
Mortgages payable     $ 135,000  
Number of properties collateral for debt | Property     16  
California [Member] | 191 III Holdings LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   6    
California [Member] | 191 III Holdings LLC [Member] | Storage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of storage facilities acquired | Property     6  
Mortgages payable     $ 57,200  
Payment for property acquisition     $ 104,100  
North Carolina [Member] | Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
Virginia [Member] | Life Storage-HIERS Storage LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
New York [Member] | SNL/Orix 1200 McDonald Ave., LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
New York [Member] | SNL Orix Merrick, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1    
New York [Member] | Review Avenue Partners LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Number of self-storage facilities | Property   1