SEGMENT REPORTING - Operating Activity Within Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Operating Income (Loss)	$ 27,669	$ 20,323	$ 74,154	$ 72,166
Total segments’ profit	65,176	53,675	180,555	172,972
Office
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	47,433	44,821	136,467	133,210
Property Expenses	(13,016)	(11,595)	(36,029)	(34,989)
Operating Income (Loss)	34,417	33,226	100,438	98,221
Retail
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	24,541	20,621	69,296	67,939
Property Expenses	(5,745)	(7,795)	(19,922)	(20,033)
Operating Income (Loss)	18,796	12,826	49,374	47,906
Multifamily
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	13,085	12,564	38,376	37,852
Property Expenses	(6,213)	(5,603)	(17,197)	(16,426)
Operating Income (Loss)	6,872	6,961	21,179	21,426
Mixed-use
Segment Reporting Information [Line Items]
Revenue from Contract with Customer, Including Assessed Tax	13,227	6,368	29,942	24,225
Property Expenses	(8,136)	(5,706)	(20,378)	(18,806)
Operating Income (Loss)	$ 5,091	$ 662	$ 9,564	$ 5,419