SEGMENT REPORTING - Capital Expenditures (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 12,216	$ 23,925
Office
Segment Reporting Information [Line Items]
Capital expenditures	[1]	9,527	18,200
Retail
Segment Reporting Information [Line Items]
Capital expenditures	[1]	1,722	3,558
Multifamily
Segment Reporting Information [Line Items]
Capital expenditures	[1]	963	1,284
Mixed-use
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 4	$ 883

[1] Capital expenditures represent cash paid for capital expenditures during the period and include leasing commissions paid