MORTGAGE AND OTHER NOTES PAYABLE - MORTGAGE BY PROPERTY (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Mortgage Loans on Real Estate [Line Items]
Interest owner percentage in property	22.00%
Mortgages
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 129,044
Repayments of long-term debt	288,321
Debt default, amount	26,300
Mortgages | LIBOR plus 1.65% Mortgage Note | Cortlandt Town Center
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	0
Repayments of long-term debt	$ 83,070
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 1.65% Mortgage Note | Cortlandt Town Center | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.65%
Mortgages | 3.8% Mortgage Note | 1964 Union Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 1,463
Stated interest rate percentage	3.80%
Mortgages | 5.62% Mortgage Note | Chicago Street Retail Portfolio
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	5.62%
Repayments of long-term debt	$ 14,955
Mortgages | LIBOR plus 1.55% Mortgage Note | Heritage Shops
Mortgage Loans on Real Estate [Line Items]
Repayments of long-term debt	$ 24,456
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 1.55% Mortgage Note | Heritage Shops | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.55%
Mortgages | LIBOR plus 1.70% Mortgage Note | 330-340 River Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 12,000
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 1.70% Mortgage Note | 330-340 River Street | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	1.70%
Mortgages | 5.24% Mortgage Note | 330-340 River Street
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	5.24%
Repayments of long-term debt	$ 10,336
Mortgages | 3.4% Mortgage Note | 2208-2216 Fillmore Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 5,606
Stated interest rate percentage	3.40%
Mortgages | 3.4% Mortgage Note | 1861 Union Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 2,315
Stated interest rate percentage	3.40%
Mortgages | 6.0% Mortgage Note | Brandywine Portfolio
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	6.00%
Repayments of long-term debt	$ 139,950
Mortgages | LIBOR plus 3.25% Mortgage Note | Sherman Avenue
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 14,250
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 3.25% Mortgage Note | Sherman Avenue | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	3.25%
Mortgages | LIBOR plus 3.4% Mortgage Note | 146 Geary Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 27,700
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 3.4% Mortgage Note | 146 Geary Street | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	3.40%
Mortgages | 4.4% Mortgage Note | Concord and Milwaukee
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 2,902
Stated interest rate percentage	4.40%
Mortgages | 4.4% Mortgage Note | State and Washington
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 25,651
Stated interest rate percentage	4.40%
Mortgages | 4.0% Mortgage Note | 151 North State Street
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 14,556
Stated interest rate percentage	4.00%
Mortgages | 4.0% Mortgage Note | North & Kingsbury
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 13,409
Stated interest rate percentage	4.00%
Mortgages | LIBOR plus 2.35% Mortgage Note | Restaurants at Fort Point
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 6,500
Description of variable rate basis	LIBOR
Mortgages | LIBOR plus 2.35% Mortgage Note | Restaurants at Fort Point | LIBOR
Mortgage Loans on Real Estate [Line Items]
Basis spread on variable rate	2.35%
Mortgages | 5.9% Mortgage Note | California and Armitage
Mortgage Loans on Real Estate [Line Items]
Debt instrument face amount	$ 2,692
Stated interest rate percentage	5.90%
Mortgages | 6.35% Mortgage Note | Acadia Brentwood LLC
Mortgage Loans on Real Estate [Line Items]
Stated interest rate percentage	6.35%
Repayments of long-term debt	$ 15,554