NONCONTROLLING INTERESTS - Interests in Consolidated Real Estate Joint Ventures (Details) $ in Thousands			1 Months Ended	9 Months Ended	12 Months Ended
	Aug. 17, 2021 USD ($)	Apr. 16, 2021 USD ($)	Mar. 31, 2021 facility	Sep. 30, 2022 USD ($) facility	Dec. 31, 2021 USD ($)
Variable Interest Entity [Line Items]
Total assets				$ 6,371,170	$ 6,548,079
Total liabilities				$ 3,446,907	$ 3,549,699
Joint Venture
Variable Interest Entity [Line Items]
Ownership interest held by the entity (as a percent)					90.00%
VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				6
Total assets				$ 163,113
Total liabilities				$ 80,916
Astoria Investors, LLC
Variable Interest Entity [Line Items]
Ownership interest held by the entity (as a percent)	70.00%
Contribution To Real Estate Venture	$ 14,700
Astoria Investors, LLC | Texas
Variable Interest Entity [Line Items]
Payments to acquire land for development	$ 20,000
Astoria Investors, LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)				70.00%
Total assets				$ 22,595
Total liabilities				7,991
Carrying amount of mortgage loans				7,700
Amount of mortgage loan commitment				$ 27,100
CS Vienna LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)				80.00%
Total assets				$ 32,944
Total liabilities				35,160
Carrying amount of mortgage loans				34,900
CS 750 W Merrick Rd LLC
Variable Interest Entity [Line Items]
Option to put ownership interest in the venture				17,100
Accretion Liability				$ 17,100
CS 750 W Merrick Rd LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)				51.00%
Total assets				$ 37,625
Total liabilities				$ 17,255
CS Valley Forge Village Storage LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)				70.00%
Total assets				$ 20,667
Total liabilities				14,633
Carrying amount of mortgage loans				$ 14,600
SH3, LLC
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)				90.00%
Total assets				$ 38,141
Total liabilities				$ 262
SH3, LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility			2
C S Lock Up Anoka LLC | VIE
Variable Interest Entity [Line Items]
Number of self-storage facilities owned and operated | facility				1
Ownership interest held by the entity (as a percent)		50.00%		50.00%
Contribution To Real Estate Venture		$ 3,400
Total assets				$ 11,141
Total liabilities				5,615
Carrying amount of mortgage loans				5,500
Amount of mortgage loan commitment				$ 6,100
C S Lock Up Anoka LLC | VIE | Minnesota
Variable Interest Entity [Line Items]
Purchase Price		$ 12,000