SEGMENT REPORTING - Operating Activity Within Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
OPERATING INCOME	$ 25,484	$ 23,510	$ 72,831	$ 70,258
Total Segments' profit	47,989	45,628	139,446	132,573
Total Retail
Segment Reporting Information [Line Items]
Property revenue	25,064	24,970	74,316	73,384
Property expense	(7,159)	(6,827)	(20,203)	(19,085)
OPERATING INCOME	17,905	18,143	54,113	54,299
Total Office
Segment Reporting Information [Line Items]
Property revenue	25,818	25,008	76,416	72,621
Property expense	(8,146)	(7,198)	(23,395)	(21,007)
OPERATING INCOME	17,672	17,810	53,021	51,614
Total Multifamily
Segment Reporting Information [Line Items]
Property revenue	8,053	4,999	21,407	13,754
Property expense	(3,288)	(2,126)	(8,960)	(5,252)
OPERATING INCOME	4,765	2,873	12,447	8,502
Total Mixed-Use
Segment Reporting Information [Line Items]
Property revenue	17,041	16,312	46,387	44,334
Property expense	(9,394)	(9,510)	(26,522)	(26,176)
OPERATING INCOME	$ 7,647	$ 6,802	$ 19,865	$ 18,158