ORGANIZATION AND BASIS OF PRESENTATION (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) property	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) property	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Reallocation of noncontrolling interest	$ 38,800,000		$ 0		$ 31,800,000
Number of retail properties (in properties) | property	168		168
Impairment of asset	$ 0	$ 5,000,000	$ 0	$ 5,000,000
Brandywine Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Noncontrolling interest, ownership percentage		77.78%		77.78%
Impairment of asset		$ 5,000,000
Core Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties (in properties) | property	110		110
Impairment of asset		5,000,000		$ 5,000,000
Opportunity Funds
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties (in properties) | property	58		58
Impairment of asset		0		$ 0
Operating Partnership | Brandywine Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Impairment of asset		$ 1,100,000
Mortgages
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument face amount	$ 21,384,000		$ 21,384,000
Non-Recourse Mortgage Debt Due 2016 | Mortgages
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument face amount	$ 26,300,000.0		$ 26,300,000.0
Operating Partnership, as General Partner or Managing Member
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Ownership interest by general partner or managing partner			94.00%
Remaining funds rate of distribution to partnership	20.00%		20.00%
Institutional Investors
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Remaining funds rate of distribution to all partners	80.00%		80.00%