SEGMENT REPORTING - Capital Expenditures (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 24,838	$ 15,208	$ 37,054	$ 39,133
Office
Segment Reporting Information [Line Items]
Capital expenditures	[1]	21,343	9,281	30,870	27,481
Retail
Segment Reporting Information [Line Items]
Capital expenditures	[1]	1,778	2,805	3,500	6,363
Multifamily
Segment Reporting Information [Line Items]
Capital expenditures	[1]	1,033	860	1,996	2,144
Mixed-use
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 684	$ 2,262	$ 688	$ 3,145

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