ACQUISITION OF REAL ESTATE AND DISCONTINUED OPERATIONS Dispositions (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014 sqft
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area	394,323
Proceeds from sale of real estate held-for-investment, gross	$ 46.5
Gain on disposition of property	13.5
Walnut Hill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Non-recourse Debt	22.9
Other post-sale adjustments
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area	0
Proceeds from sale of real estate held-for-investment, gross	0
Gain on disposition of property	(0.9)
Core Portfolio | Walnut Hill
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area	297,905	[1]
Proceeds from sale of real estate held-for-investment, gross	0	[1]
Gain on disposition of property	12.4	[1]
Fund III | Sheepshead Bay
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area	96,418
Proceeds from sale of real estate held-for-investment, gross	20.2
Gain on disposition of property	1.4
Fund II | City Point
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area	0	[2]
Proceeds from sale of real estate held-for-investment, gross	26.3	[2]
Gain on disposition of property	$ 0.6	[2]

[1] This property was subject to $22.9 million of non-recourse debt and was foreclosed upon by the lender during March 2014, resulting in a $12.4 million gain.

[2] Represents the sale of a portion of the residential air rights known as "Tower 2" associated with the Company's City Point development project.