RELATED PARTY TRANSACTIONS - Costs (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Payable as of	$ 4,025,000		$ 4,025,000		$ 1,635,000
Payment for administrative fees	0	$ 62,000	0	$ 133,000
Pacific Oak Capital Advisors LLC
Related Party Transaction [Line Items]
Capitalized	2,837,000	3,001,000	5,134,000	5,374,000
Payable as of	4,025,000		4,025,000		1,635,000
Pacific Oak Capital Advisors LLC | Asset management fees
Related Party Transaction [Line Items]
Expensed	2,336,000	1,971,000	4,441,000	3,861,000
Payable as of	4,008,000		4,008,000		1,498,000
Pacific Oak Capital Advisors LLC | Reimbursable operating expenses
Related Party Transaction [Line Items]
Expensed	0	83,000	93,000	172,000
Payable as of	0		0		0
Pacific Oak Capital Advisors LLC | Disposition fees
Related Party Transaction [Line Items]
Expensed	0	0	0	394,000
Payable as of	0		0		0
Pacific Oak Capital Advisors LLC | Subordinated performance fee due upon termination to affiliate
Related Party Transaction [Line Items]
Expensed	307,000	0	307,000	0
Pacific Oak Capital Advisors LLC | Acquisition fees on real estate equity securities
Related Party Transaction [Line Items]
Capitalized	23,000	0	122,000	0
Payable as of	17,000		17,000		0
Pacific Oak Capital Advisors LLC | Acquisition fee on real estate
Related Party Transaction [Line Items]
Capitalized	171,000	897,000	171,000	897,000
Payable as of	0		0		0
Pacific Oak Capital Advisors LLC | Acquisition fee on investment in unconsolidated entities
Related Party Transaction [Line Items]
Capitalized	0	$ 50,000	0	$ 50,000
Payable as of	$ 0		$ 0		$ 137,000