ORGANIZATION (Details)		3 Months Ended		47 Months Ended	62 Months Ended
	Aug. 11, 2015 USD ($) shares	Mar. 31, 2020 USD ($) numberOfInvestments numberOfProperties shares	Mar. 31, 2019 USD ($) shares	Mar. 31, 2020 USD ($) numberOfInvestments numberOfProperties shares	Mar. 31, 2020 USD ($) numberOfInvestments numberOfProperties shares	Dec. 31, 2019 shares	Oct. 03, 2017 shares	Jun. 11, 2015 shares	Feb. 04, 2015 USD ($)	Jan. 27, 2015 $ / shares shares
Organizational Structure [Line Items]
Number of investments in unconsolidated joint venture | numberOfInvestments		1		1	1
Core property, minimum percent of occupancy		80.00%		80.00%	80.00%
Issuance of common stock | $		$ 269,000	$ 1,667,000
Redemptions of common stock | $			$ 21,000
Class A Common Stock
Organizational Structure [Line Items]
Common stock, shares issued (in shares)		9,870,515		9,870,515	9,870,515	9,841,004
Class T Common Stock
Organizational Structure [Line Items]
Common stock, shares issued (in shares)		308,712		308,712	308,712	306,292
Maximum | Class A Common Stock | Second Private Placement
Organizational Structure [Line Items]
Shares authorized for issuance							1,000,000,000
Common Stock | Public Offering
Organizational Structure [Line Items]
Issuance of common stock | $					$ 3,900,000
Stock issued during period, dividend reinvestment plan | $					$ 8,200,000
Common Stock | Class A Common Stock
Organizational Structure [Line Items]
Shares authorized for dividend reinvestment plan								5,000,000
Issuance of common stock (in shares)	46,362	29,511	177,957
Issuance of common stock | $	$ 300,000	$ 1,000	$ 2,000
Redemptions of common stock (in shares)					422,286
Redemptions of common stock | $					$ 3,500,000
Common Stock | Class A Common Stock | Private Placement
Organizational Structure [Line Items]
Issuance of common stock (in shares)				8,548,972
Issuance of common stock | $				$ 76,800,000
Stock issued during period, dividend reinvestment plan (in shares)				74,744
Stock issued during period, dividend reinvestment plan | $				$ 700,000
Common Stock | Class A Common Stock | Public Offering
Organizational Structure [Line Items]
Issuance of common stock (in shares)					122,721
Stock issued during period, dividend reinvestment plan (in shares)					855,475
Common Stock | Class A Common Stock | Second Private Offering
Organizational Structure [Line Items]
Issuance of common stock (in shares)				612,272
Issuance of common stock | $				$ 5,500,000
Common Stock | Class T Common Stock
Organizational Structure [Line Items]
Issuance of common stock (in shares)		2,420	3,296
Redemptions of common stock (in shares)			2,245		2,245
Common Stock | Class T Common Stock | Public Offering
Organizational Structure [Line Items]
Issuance of common stock (in shares)					270,415
Stock issued during period, dividend reinvestment plan (in shares)					38,768
Common Stock | Maximum
Organizational Structure [Line Items]
Shares authorized for issuance, value | $									$ 1,500,000,000
Shares authorized for dividend reinvestment plan | $									$ 800,000,000
Common Stock | Maximum | Class A Common Stock
Organizational Structure [Line Items]
Shares authorized for issuance								105,000,000
Office Building
Organizational Structure [Line Items]
Number of real estate properties | numberOfProperties		3		3	3
KBS Capital Advisors LLC
Organizational Structure [Line Items]
Common stock, shares issued (in shares)										20,000
Purchase price per share (in usd per share) | $ / shares										$ 10.00
KBS Growth & Income Limited Partnership
Organizational Structure [Line Items]
Managing member or general partner, ownership interest		0.10%
Members or limited partners, ownership interest		99.90%