ACQUISITION AND DISPOSITION OF REAL ESTATE AND PROPERTIES HELD FOR SALE - Dispositions & Properties Held For Sale (Details) ft² in Thousands, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016 USD ($) ft² property	Dec. 31, 2015 property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area (in square feet) | ft²	82,098
Sale Price	$ 153,750
Gain on Sale	$ 81,965
Number of properties held for sale | property	0	0
Fund III | Cortlandt Town Center
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area (in square feet) | ft²	0
Disposal group, percentage	65.00%
Sale Price	$ 107,250
Gain on Sale	$ 65,393
Fund III | Heritage Shops
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gross leasable area (in square feet) | ft²	82,098
Sale Price	$ 46,500
Gain on Sale	$ 16,572