REAL ESTATE HELD FOR INVESTMENT (Highest Tenant Industry Concentrations- Grater than 10% of Annual Base Rent) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) tenant
Concentration Risk [Line Items]
Number of Tenants | tenant	185
Annualized Base Rent | $	$ 56,873
Percentage of Annualized Base Rent	47.50%
Finance
Concentration Risk [Line Items]
Number of Tenants | tenant	32
Annualized Base Rent | $	$ 27,831
Percentage of Annualized Base Rent	23.20%
Legal Services
Concentration Risk [Line Items]
Number of Tenants | tenant	32
Annualized Base Rent | $	$ 15,092
Percentage of Annualized Base Rent	12.60%
Mining, Oil & Gas Extraction
Concentration Risk [Line Items]
Number of Tenants | tenant	4
Annualized Base Rent | $	$ 13,950
Percentage of Annualized Base Rent	11.70%