COMMITMENTS AND CONTINGENCIES (Details) - KBS Capital Advisors LLC $ in Millions	Sep. 30, 2018 USD ($)
Related Party Transaction [Line Items]
Noncompounded return on invested capital as percent per year, percent	7.00%
Percent of net cash flows to be received by related party, percent	15.00%
Distributions paid from operating cash flows, annual return, percent	7.00%
Incentive Compensation
Related Party Transaction [Line Items]
Liabilities at fair value	$ 43