SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands		9 Months Ended
	Jul. 01, 2024 USD ($) shares	Sep. 30, 2024 USD ($) property partnership shares	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Jan. 03, 2023 USD ($)	Jan. 02, 2023 USD ($)
Variable Interest Entity [Line Items]
Maximum borrowing capacity		$ 1,355,000
Borrowings under debt financings		$ 1,099,000	$ 928,800
Number of self storage properties | property		1,070
Net book value of real estate owned		$ 4,814,821		$ 4,917,815
Carrying value of fixed rate mortgages		$ 3,438,947		3,668,757
Consideration for internalization of PRO structure	$ 34,600
Merger and internalization of PRO, net of issuance costs (in shares) | shares	775,210
Cash payment	$ 3,400
Consideration paid for PRO rights	$ 60,300
Redemptions/conversions of units (in shares) | shares	11,906,167
Consideration for PRO rights, cash payments	$ 29,200
Transaction fees	$ 1,400
Issuance of preferred shares (in shares) | shares	17,984,787	40,200
Time frame prior to conversion for conversion metric (in years)	1 year
Percentage of cash available for distribution used in conversion ratio calculation	110.00%
OP Units
Variable Interest Entity [Line Items]
Redemptions/conversions of units (in shares) | shares	773,656
VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Number of partnerships considered to be VIEs | partnership		22
Number of self storage properties | property		49
Net book value of real estate owned		$ 410,000		418,900
Credit Facility | Credit Facility
Variable Interest Entity [Line Items]
Maximum borrowing capacity					$ 1,955,000	$ 405,000
Borrowings under debt financings			$ 129,800
Fixed rate mortgages payable | Fixed rate mortgages payable
Variable Interest Entity [Line Items]
Carrying value of fixed rate mortgages		217,147		222,757
Fixed rate mortgages payable | Fixed rate mortgages payable | VIE, Primary Beneficiary
Variable Interest Entity [Line Items]
Carrying value of fixed rate mortgages		$ 188,700		$ 188,700