INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Narrative (Details) storage_unit in Thousands, ft² in Millions	Mar. 31, 2026 ft² storage_unit state property	Mar. 16, 2026 property
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	1,061	313
Total rentable square feet in self storage properties \| ft²	69.3
Number of states in which self storage properties are located \| state	37
Number of units in real estate property \| storage_unit	547
Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	262
Total rentable square feet in self storage properties \| ft²	18.2
Number of states in which self storage properties are located \| state	24
Number of units in real estate property \| storage_unit	145
2018 Joint Venture \| Unconsolidated properties
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (as a percent)	25.00%
2018 Joint Venture \| Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (as a percent)	25.00%
Number of self storage properties	104
Total rentable square feet in self storage properties \| ft²	7.9
Number of states in which self storage properties are located \| state	17
Number of units in real estate property \| storage_unit	65
2024 Joint Venture \| Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	56
Total rentable square feet in self storage properties \| ft²	3.2
Number of storage units \| storage_unit	24
Number of states in which self storage properties are located \| state	7
2023 Joint Venture \| Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties	21
Total rentable square feet in self storage properties \| ft²	1.4
Number of states in which self storage properties are located \| state	5
Number of units in real estate property \| storage_unit	9
2016 Joint Venture \| Unconsolidated properties
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (as a percent)	25.00%
2016 Joint Venture \| Unconsolidated properties \| Joint Venture
Schedule of Equity Method Investments [Line Items]
Company's equity interest in unconsolidated real estate ventures (as a percent)	25.00%
Number of self storage properties	81
Total rentable square feet in self storage properties \| ft²	5.7
Number of states in which self storage properties are located \| state	13
Number of units in real estate property	47,000

Number of Storage Units

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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
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-Name Accounting Standards Codification
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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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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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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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