RELATED PARTY TRANSACTIONS (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	May 29, 2015 USD ($) ft² $ / ft²
KBS Capital Advisors LLC
Related Party Transaction [Line Items]
Expenses			$ 100	$ 100
KBS Capital Advisors LLC | Property Insurance Rebate
Related Party Transaction [Line Items]
Incurred	$ 200	$ 200	200	200
KBS Capital Advisors LLC | Legal and Professional Fees Reimbursement
Related Party Transaction [Line Items]
Incurred		100		100
Affiliated Entity | Subsidiaries
Related Party Transaction [Line Items]
Net rentable area | ft²					5,046
Percent of total rentable square feet					2.30%
Annualized base rent					$ 200
Average annualized base rent per square foot | $ / ft²					46.38
Rental income	$ 60	$ 59	$ 120	$ 117