SEGMENT REPORTING - Capital Expenditures (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 13,383	$ 16,522	$ 36,793	$ 38,499
Retail
Segment Reporting Information [Line Items]
Capital expenditures	[1]	3,221	3,803	8,678	7,849
Office
Segment Reporting Information [Line Items]
Capital expenditures	[1]	9,407	10,555	24,293	25,715
Multifamily
Segment Reporting Information [Line Items]
Capital expenditures	[1]	536	1,953	3,020	4,521
Mixed-Use
Segment Reporting Information [Line Items]
Capital expenditures	[1]	$ 219	$ 211	$ 802	$ 414

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