RELATED PARTY TRANSACTIONS (Narrative) (Details) - USD ($)		12 Months Ended
	Nov. 01, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 16, 2017	Feb. 17, 2016
Pacific Oak Opportunity Zone Fund I, LLC
Related Party Transaction [Line Items]
Investments		$ 2,900,000
Private Placement
Related Party Transaction [Line Items]
Offering costs (other than selling commissions and dealer manager fees)		1,000,000.0
Selling commissions and dealer manager fees		1,900,000
IPO
Related Party Transaction [Line Items]
Selling commissions and dealer manager fees		14,500,000
Due to officers or stockholders		1,700,000
Other organization and offering costs		2,300,000
Organization and offering costs incurred by related party		11,400,000
Follow-on Offering | KBS Capital Advisors LLC
Related Party Transaction [Line Items]
Organization and offering costs incurred by related party		$ 100,000
Minimum | IPO | KBS Capital Advisors LLC
Related Party Transaction [Line Items]
Percent of aggregate gross proceeds		15.00%
Reimbursable offering costs determination, gross offering costs, percentage		1.00%
Dealer Manager Agreement | Common Stock
Related Party Transaction [Line Items]
Selling commission fees reallowed as percent of stockholders' servicing fee						100.00%
Reallowed broker-dealer fee as percent of gross offering proceeds						1.00%
Marketing fee as percent of gross primary offering proceeds						1.50%
Dealer Manager Agreement | Common Stock | Common Class T
Related Party Transaction [Line Items]
Selling commission fees reallowed as percent of stockholders' servicing fee						100.00%
Stockholder servicing fee, percent of total purchase price						1.00%
Stockholder servicing fee		$ 0
Dealer Manager Agreement | Maximum | Common Stock
Related Party Transaction [Line Items]
Selling commissions fee as percent of purchase price					6.50%
Dealer manager fee as percent of purchase price					3.00%	2.00%
Dealer Manager Agreement | Maximum | Common Stock | Common Class A
Related Party Transaction [Line Items]
Selling commissions fee as percent of purchase price						6.50%
Dealer Manager Agreement | Maximum | Common Stock | Common Class T
Related Party Transaction [Line Items]
Selling commissions fee as percent of purchase price						3.00%
Property Insurance Rebate | KBS Capital Advisors LLC
Related Party Transaction [Line Items]
Incurred			$ 35,000
KBS Capital Advisors LLC
Related Party Transaction [Line Items]
Term of advisory agreement	1 year
Renewal period	1 year
KBS Capital Advisors LLC | Legal and Professional Fees Reimbursement and Property Insurance Rebate
Related Party Transaction [Line Items]
Due from related parties				$ 100,000
Pacific Oak Capital Advisors, LLC
Related Party Transaction [Line Items]
Acquisition fee, percent		1.50%
Benchmark amount of contracted acquisition sales price		$ 25,000,000.0
Acquisition fee as percent of benchmark contract sales price		1.00%
Quarterly asset management fee		0.25%
Financing fee		0.50%