SEGMENT REPORTING - Operating Activity Within Reportable Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
OPERATING INCOME	$ 23,704	$ 23,504	$ 47,347	$ 46,748
Total Segments' profit	45,812	43,578	91,457	86,945
Total Retail
Segment Reporting Information [Line Items]
Property revenue	24,881	24,376	49,252	48,414
Property expense	(6,964)	(6,258)	(13,044)	(12,258)
OPERATING INCOME	17,917	18,118	36,208	36,156
Total Office
Segment Reporting Information [Line Items]
Property revenue	25,278	24,036	50,598	47,613
Property expense	(7,547)	(6,988)	(15,249)	(13,809)
OPERATING INCOME	17,731	17,048	35,349	33,804
Total Multifamily
Segment Reporting Information [Line Items]
Property revenue	7,060	4,445	13,354	8,755
Property expense	(2,852)	(1,642)	(5,672)	(3,126)
OPERATING INCOME	4,208	2,803	7,682	5,629
Total Mixed-Use
Segment Reporting Information [Line Items]
Property revenue	14,600	13,912	29,346	28,022
Property expense	(8,644)	(8,303)	(17,128)	(16,666)
OPERATING INCOME	$ 5,956	$ 5,609	$ 12,218	$ 11,356