COMMITMENTS AND CONTINGENCIES (Details) - KBS Capital Advisors LLC	Mar. 31, 2021 USD ($)
Related Party Transaction [Line Items]
Percent of net cash flows to be received by related party	15.00%
Noncompounded return on invested capital as percent per year	8.00%
Distributions paid from operating cash flow in excess of cumulative, noncompounded, annual return, percent	8.00%
Nonfinancial liabilities	$ 0