ACQUISITION OF REAL ESTATE AND DISCONTINUED OPERATIONS Dispositions (Details) (USD $)	9 Months Ended		9 Months Ended
	Sep. 30, 2014 sqft	Mar. 31, 2014 Walnut Hill	Sep. 30, 2014 Core Portfolio Walnut Hill sqft		Sep. 30, 2014 Core Portfolio Union Plaza sqft	Sep. 30, 2014 Fund III Sheepshead Bay sqft	Sep. 30, 2014 Fund III Lincoln Road Portfolio sqft		Sep. 30, 2014 Fund II City Point sqft		Sep. 30, 2014 Fund II Other post-sale adjustments sqft	Sep. 30, 2014 Fund IV Lincoln Road Portfolio sqft
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area (in square feet)	510,219		297,905	[1]	0	96,418	61,443	[2]	0	[3]	0	54,453	[2]
Sale Price	$ 388,840,000		$ 0	[1]	$ 340,000	$ 20,200,000	$ 141,800,000	[2]	$ 26,300,000	[3]	$ 0	$ 200,200,000	[2]
Gain/Loss on Sale	154,940,000		12,402,000	[1]	190,000	1,399,000	86,600,000	[2]	561,000	[3]	(854,000)	54,642,000	[2]
Non-recourse Debt		$ 22,900,000

[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] Both the Fund III and Fund IV Lincoln Road Portfolios were unconsolidated and as such, the Company's share of gains related to these sales are included in gain on disposition of properties of unconsolidated affiliates in the 2014 Consolidated Statement of Income.

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