Quarterly report pursuant to Section 13 or 15(d)

ORGANIZATION AND NATURE OF OPERATIONS (Details)

v3.21.2
ORGANIZATION AND NATURE OF OPERATIONS (Details)
storage_unit in Thousands, ft² in Millions
9 Months Ended
Sep. 30, 2021
ft²
state
property
storage_unit
metropolitan_statistical_area
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 940  
Number of states in which self storage properties are located | state 38  
Total rentable square feet in self storage properties | ft² 60.4  
Number of storage units | storage_unit 474  
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 763  
Number of states in which self storage properties are located | state 35  
Total rentable square feet in self storage properties | ft² 47.6  
Number of storage units | storage_unit 370  
Unconsolidated properties | Joint venture | Unconsolidated real estate ventures    
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 | Joint venture | 2016 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 | Joint venture | 2018 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