INVESTMENT IN UNCONSOLIDATED VENTURES - Income Statement Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Rental and other revenue from real estate properties	$ 7,029	$ 7,020	$ 6,657	$ 6,745	$ 6,765	$ 6,261	$ 7,097	$ 6,886	$ 27,451	$ 27,009
Total revenues	7,049	7,313	6,816	6,924	6,922	6,422	7,287	7,130	28,102	27,761
Expenses:
Real estate operating expenses	3,026	3,289	3,004	3,058	3,090	2,741	3,325	3,176	12,377	12,332
Interest expense	1,700	1,731	1,809	1,860	1,931	1,870	2,049	1,946	7,100	7,796
Depreciation	1,595	1,777	1,809	1,561	1,568	1,373	1,428	1,547	6,742	5,916
Total expenses	8,968	13,169	9,579	9,846	9,225	8,414	9,283	9,213	41,562	36,135
Total revenues less total expenses	(1,919)	(5,856)	(2,763)	(2,922)	(2,303)	(1,992)	(1,996)	(2,083)	(13,460)	(8,374)
Gain on sale of real estate					680	9,938	0	0	0	10,618
Loss on extinguishment of debt					0	(1,387)	0	0	0	(1,387)
Net (loss) income from joint ventures	33	34	31	32	(40)	799	44	34	130	837
Net (loss) income attributable to common stockholders	$ (3,301)	$ (7,484)	$ (4,246)	$ (4,831)	$ 6,148	$ 3,272	$ (4,317)	$ (4,247)	(19,862)	856
Unconsolidated joint ventures
Revenues:
Rental and other revenue from real estate properties									127,058	118,177
Total revenues									127,058	118,177
Expenses:
Real estate operating expenses									60,326	56,684
Interest expense									34,918	35,023
Depreciation									41,657	39,218
Total expenses									136,901	130,925
Total revenues less total expenses									(9,843)	(12,748)
Other equity earnings									117	177
Gain on sale of real estate									0	16,899
Loss on extinguishment of debt									0	(2,018)
Gain on insurance recovery									765	787
Net (loss) income from joint ventures									(8,961)	3,097
Net (loss) income attributable to common stockholders									$ (6,024)	$ 1,106