SEGMENT REPORTING - Capital Expenditures (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Capital Expenditures	$ 44,968	[1]	$ 31,296	[1]
Total Retail
Segment Reporting Information [Line Items]
Capital Expenditures	935	[1]	1,506	[1]
Total Office
Segment Reporting Information [Line Items]
Capital Expenditures	14,714	[1]	7,091	[1]
Total Multifamily
Segment Reporting Information [Line Items]
Capital Expenditures	28,948	[1]	21,877	[1]
Total Mixed-Use
Segment Reporting Information [Line Items]
Capital Expenditures	$ 371	[1]	$ 822	[1]

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