INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Narrative (Details) storage_unit in Thousands, $ in Thousands, ft² in Millions	3 Months Ended
Mar. 31, 2024 USD ($) ft² property storage_unit state	Dec. 31, 2023 USD ($) extension_period
Schedule of Equity Method Investments [Line Items]
Number of self storage properties \| property	1,050
Number of states in which self storage properties are located \| state	42
Rentable square feet in self storage properties \| ft²	68.7
Investment in unconsolidated real estate ventures	$ 240,025	$ 211,361
Number of units in real estate property \| storage_unit	542
2024 Joint Venture
Schedule of Equity Method Investments [Line Items]
Real estate investments, joint ventures	$ 210,000
Company's equity interest in unconsolidated real estate ventures (percent)	6.05%
Real estate investments, joint ventures, maturity period	5 years
2023 Joint Venture
Schedule of Equity Method Investments [Line Items]
Real estate investments, joint ventures, maturity period		24 months
Number of extension periods \| extension_period		2
Extension period		6 months
Joint Venture \| 2024 Joint Venture
Schedule of Equity Method Investments [Line Items]
Real estate investments, joint ventures	$ 140,800
2024 NSA Member \| 2024 Joint Venture
Schedule of Equity Method Investments [Line Items]
Real estate investments, joint ventures	$ 35,200
Company's equity interest in unconsolidated real estate ventures (percent)	25.00%
2024 JV Investor \| 2024 Joint Venture
Schedule of Equity Method Investments [Line Items]
Real estate investments, joint ventures	$ 105,600
Company's equity interest in unconsolidated real estate ventures (percent)	75.00%
Number of self storage properties \| property	56
Number of states in which self storage properties are located \| state	7
Rentable square feet in self storage properties \| ft²	3.2
Number of storage units \| storage_unit	24
2023 JV Members \| 2023 Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (percent)		75.00%
Investment in unconsolidated real estate ventures		$ 400,000
2023 NSA Member \| 2023 Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (percent)		25.00%
Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties \| property	241
Number of states in which self storage properties are located \| state	24
Rentable square feet in self storage properties \| ft²	16.7
Number of units in real estate property \| storage_unit	135
Unconsolidated properties \| Joint Venture \| 2018 Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (percent)	25.00%
Number of self storage properties \| property	104
Number of states in which self storage properties are located \| state	17
Rentable square feet in self storage properties \| ft²	7.8
Number of units in real estate property \| storage_unit	64
Unconsolidated properties \| Joint Venture \| 2016 Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (percent)	25.00%
Number of self storage properties \| property	81
Number of states in which self storage properties are located \| state	13
Rentable square feet in self storage properties \| ft²	5.7
Number of units in real estate property \| storage_unit	47

Number of Storage Units

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Real Estate Investments, Joint Ventures, Extension Period

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Net rentable area for properties owned.

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The number of real estate properties owned as of the balance sheet date.

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The number of states the entity operates in as of the balance sheet date.

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The number of units in a real estate property owned as of the balance sheet date.

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The book value of investments in real estate joint ventures including direct and indirect investments.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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