MORTGAGE AND OTHER NOTES PAYABLE - MORTGAGE BY PROPERTY (Details) - Mortgages	9 Months Ended
	Sep. 30, 2015 USD ($)
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 171,765,000
Repayments of long-term debt	76,128,000
Libor Plus 2.25% Mortgage Note | 1035 Third Avenue
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 42,000,000
Description of variable rate basis	LIBOR
Libor Plus 2.25% Mortgage Note | 1035 Third Avenue | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	2.35%
Libor Plus 1.45% Mortgage Note | Lincoln Park Centre
Mortgage Loans on Real Estate [Line Items]
Description of variable rate basis	LIBOR
Repayments of long-term debt	$ 28,000,000
Libor Plus 1.45% Mortgage Note | Lincoln Park Centre | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.45%
4.66% Mortgage note | 163 Highland Avenue
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 9,765,000
Stated interest rate percentage	4.66%
Libor Plus 3% Mortgage Note | Broughton Street Portfolio
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 20,000,000
Libor Plus 3% Mortgage Note | Broughton Street Portfolio | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	2.95%
1.25% Mortgage Note | City Point
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 19,000,000
Stated interest rate percentage	1.25%
Sifma Plus 1.6% Mortgage Note | City Point
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 62,000,000
Sifma Plus 1.6% Mortgage Note | City Point | SIFMA
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.60%
Libor Plus 4% Mortgage Note | City Point
Mortgage Loans on Real Estate [Line Items]
Repayments of long-term debt	$ 20,650,000
Libor Plus 4% Mortgage Note | City Point | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	4.00%
Libor Plus 1.9% Mortgage Note | 17 E. 71st Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 19,000,000
Libor Plus 1.9% Mortgage Note | 17 E. 71st Street | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.90%
4.98% Mortgage Note | Crescent Plaza
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	4.98%
Repayments of long-term debt	$ 16,326,000
5.13% Mortgage Note | Pacesetter Park Shopping Center
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	5.13%
Repayments of long-term debt	$ 11,152,000