SEGMENT REPORTING - Capital Expenditures (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 15,208	$ 28,024	$ 39,133	$ 50,461
Office
Segment Reporting Information [Line Items]
Capital expenditures	[1]	9,281	17,418	27,481	33,901
Retail
Segment Reporting Information [Line Items]
Capital expenditures	[1]	2,805	6,650	6,363	11,441
Multifamily
Segment Reporting Information [Line Items]
Capital expenditures	[1]	860	685	2,144	1,456
Mixed-use
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 2,262	$ 3,271	$ 3,145	$ 3,663

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