SEGMENT REPORTING - Capital Expenditures (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 12,045	$ 13,822	$ 23,410	$ 21,977
Retail
Segment Reporting Information [Line Items]
Capital expenditures	[1]	3,228	2,800	5,457	4,046
Office
Segment Reporting Information [Line Items]
Capital expenditures	[1]	7,513	8,800	14,886	15,160
Multifamily
Segment Reporting Information [Line Items]
Capital expenditures	[1]	875	2,109	2,484	2,568
Mixed-Use
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 429	$ 113	$ 583	$ 203

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