SEGMENT REPORTING - Operating Activity Within Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting Information [Line Items]
OPERATING INCOME	$ 23,510	$ 23,036	$ 70,258	$ 61,143
Total Segments' profit	45,628	44,070	132,573	125,974
Total Retail
Segment Reporting Information [Line Items]
Property revenue	24,970	24,177	73,384	70,746
Property expense	(6,827)	(6,197)	(19,085)	(18,703)
OPERATING INCOME	18,143	17,980	54,299	52,043
Total Office
Segment Reporting Information [Line Items]
Property revenue	25,008	23,416	72,621	68,721
Property expense	(7,198)	(6,813)	(21,007)	(19,791)
OPERATING INCOME	17,810	16,603	51,614	48,930
Total Multifamily
Segment Reporting Information [Line Items]
Property revenue	4,999	4,320	13,754	12,660
Property expense	(2,126)	(1,532)	(5,252)	(4,513)
OPERATING INCOME	2,873	2,788	8,502	8,147
Total Mixed-Use
Segment Reporting Information [Line Items]
Property revenue	16,312	15,430	44,334	41,395
Property expense	(9,510)	(8,731)	(26,176)	(24,541)
OPERATING INCOME	$ 6,802	$ 6,699	$ 18,158	$ 16,854