SEGMENT REPORTING Net Real Estate and Secured Note Payable Balances (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Segment Reporting Information [Line Items]
Net Real Estate	$ 1,661,955		$ 1,668,182
Secured Notes Payable	1,055,840	[1]	1,057,680	[1]
Unamortized fair value adjustment	11,541		12,998
Total Retail
Segment Reporting Information [Line Items]
Net Real Estate	659,496		669,177
Secured Notes Payable	396,358	[1]	397,732	[1]
Total Office
Segment Reporting Information [Line Items]
Net Real Estate	765,552		759,203
Secured Notes Payable	427,728	[1]	428,194	[1]
Total Multifamily
Segment Reporting Information [Line Items]
Net Real Estate	35,937		36,391
Secured Notes Payable	101,444	[1]	101,444	[1]
Total Mixed-Use
Segment Reporting Information [Line Items]
Net Real Estate	200,970		203,411
Secured Notes Payable	$ 130,310	[1]	$ 130,310	[1]

[1] Excludes unamortized fair market value adjustments of $11.5 million and $13.0 million as of June 30, 2013 and December 31, 2012, respectively.