REAL ESTATE INVESTMENTS - Schedule of Properties Classified as Held for Sale (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Real estate investments:
Accumulated depreciation	$ (1,034,681)	$ (957,450)
Total real estate investments, net	2,909,307	2,955,068
Deferred costs, net	95,470	86,862
Intangible assets, net	20,471	28,556
Total assets	3,974,187	3,846,196
LIABILITIES HELD FOR SALE
Deferred income, gains and rent	22,913	23,849
Intangible liabilities, net	10,739	12,981
Total liabilities	2,339,238	$ 2,144,977
Held-for-sale | Pennsylvania suburbs segment
Real estate investments:
Operating properties	21,050
Accumulated depreciation	(1,840)
Total real estate investments, net	19,210
Deferred costs, net	236
Intangible assets, net	88
Total assets	19,534
LIABILITIES HELD FOR SALE
Deferred income, gains and rent	20
Intangible liabilities, net	16
Total liabilities	$ 36