SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)	3 Months Ended
	Mar. 31, 2025 USD ($) property partnership	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Variable Interest Entity [Line Items]
Number of self storage properties | property	1,075
Self storage properties, net	$ 4,777,581,000		$ 4,812,496,000
Principal amount	$ 3,436,060,000		3,459,093,000
Property management fees as percent of monthly gross revenues and net sales revenue of unconsolidated real estate venture assets	4.00%
Tenant Insurance and Tenant Warranty Protection Plan Revenues
Variable Interest Entity [Line Items]
Revenue	$ 5,900,000	$ 5,600,000
Retail Products and Supplies
Variable Interest Entity [Line Items]
Revenue	400,000	500,000
Property Management, Call Center, and Platform Fees
Variable Interest Entity [Line Items]
Revenue	$ 4,700,000	4,300,000
Property management fees as percent of monthly gross revenues and net sales revenue of unconsolidated real estate venture assets	6.00%
Platform fees per unconsolidated real estate venture property per month	$ 1,250
Call center fees as percent of monthly gross revenues and net sales revenue of unconsolidated real estate venture assets	1.00%
Tenant Warranty Protection or Tenant Insurance
Variable Interest Entity [Line Items]
Revenue	$ 7,200,000	$ 4,700,000
Percent of total warranty protection plan proceeds received per unconsolidated real estate venture property	50.00%
Fixed Rate Mortgages | Mortgages
Variable Interest Entity [Line Items]
Principal amount	$ 200,260,000		200,793,000
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Number of partnerships considered to be VIEs | partnership	22
Number of self storage properties | property	49
Self storage properties, net	$ 404,200,000		407,100,000
VIE, Primary Beneficiary | Fixed Rate Mortgages | Mortgages
Variable Interest Entity [Line Items]
Principal amount	$ 172,900,000		$ 172,900,000