Quarterly report pursuant to Section 13 or 15(d)

ORGANIZATION AND NATURE OF OPERATIONS (Details)

v3.21.1
ORGANIZATION AND NATURE OF OPERATIONS (Details)
storage_unit in Thousands, ft² in Millions
3 Months Ended
Mar. 31, 2021
ft²
storage_unit
property
metropolitan_statistical_area
state
Dec. 31, 2016
property
Schedule of Equity Method Investments [Line Items]    
Number of top metropolitan statistical areas for focus of operations | metropolitan_statistical_area 100  
Number of self storage properties | property 844  
Number of states in which self storage properties are located | state 36  
Total rentable square feet in self storage properties | ft² 53.5  
Number of storage units | storage_unit 425  
2016 Joint Venture    
Schedule of Equity Method Investments [Line Items]    
Company's equity interest in unconsolidated real estate ventures (percent) 25.00%  
2018 Joint Venture    
Schedule of Equity Method Investments [Line Items]    
Company's equity interest in unconsolidated real estate ventures (percent) 25.00%  
Consolidated properties    
Schedule of Equity Method Investments [Line Items]    
Number of self storage properties | property 667  
Number of states in which self storage properties are located | state 33  
Total rentable square feet in self storage properties | ft² 40.8  
Number of storage units | storage_unit 321  
Unconsolidated properties | Unconsolidated real estate ventures | Joint venture    
Schedule of Equity Method Investments [Line Items]    
Number of self storage properties | property 177  
Number of states in which self storage properties are located | state 21  
Total rentable square feet in self storage properties | ft² 12.7  
Number of storage units | storage_unit 104  
Unconsolidated properties | 2016 Joint Venture | Joint venture    
Schedule of Equity Method Investments [Line Items]    
Number of self storage properties | property 74 66
Number of states in which self storage properties are located | state 13  
Total rentable square feet in self storage properties | ft² 4.9  
Number of storage units | storage_unit 40  
Unconsolidated properties | 2018 Joint Venture | Joint venture    
Schedule of Equity Method Investments [Line Items]    
Number of self storage properties | property 103  
Number of states in which self storage properties are located | state 17  
Total rentable square feet in self storage properties | ft² 7.8  
Number of storage units | storage_unit 64