BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accounting Policies [Abstract]
Fixed lease income - operating leases	$ 47,292	$ 41,712	$ 134,817	$ 125,555
Variable lease income - operating leases	2,171	1,729	6,243	4,811
Revenue from contracts with customers	950	697	2,657	2,088
Total revenue	$ 50,413	$ 44,138	$ 143,717	$ 132,454