INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURES - Condensed Financial Position (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
ASSETS
Self storage properties	$ 5,797,653	$ 5,792,174
Less accumulated depreciation	(919,723)	(874,359)
Self storage properties, net	4,877,930	4,917,815
Other assets	130,015	134,002
Total assets	5,366,865	5,931,811
LIABILITIES AND EQUITY
Debt financing	3,285,547	3,658,205
Equity	1,947,072	2,125,841	$ 2,405,074	$ 2,389,014
Total liabilities and equity	5,366,865	5,931,811
Joint Venture | Equity Method Investment, Nonconsolidated Investee or Group of Investees
ASSETS
Self storage properties	2,543,250	2,200,522
Less accumulated depreciation	(386,720)	(369,412)
Self storage properties, net	2,156,530	1,831,110
Other assets	42,052	37,826
Total assets	2,198,582	1,868,936
LIABILITIES AND EQUITY
Debt financing	1,212,507	1,003,223
Other liabilities	27,871	28,333
Equity	958,204	837,380
Total liabilities and equity	$ 2,198,582	$ 1,868,936