ORGANIZATION AND BASIS OF PRESENTATION (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2015 USD ($) property	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) property	Sep. 30, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties (in properties) | property	142			142
Impairment of asset	$ 0		$ 0	$ 5,000,000	$ 0
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		$ 5,000,000
Core Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties (in properties) | property	90			90
Impairment of asset				$ 5,000,000
Opportunity Funds
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties (in properties) | property	52			52
Impairment of asset				$ 0
Operating Partnership | Brandywine Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Impairment of asset		$ 1,100,000		1,100,000
Mortgages
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Debt instrument face amount	$ 171,765,000			171,765,000
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				95.00%
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%