ORGANIZATION (Details) $ in Millions	5 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($) numberOfProperties shares	Jun. 30, 2020 numberOfProperties shares	Jan. 31, 2020 numberOfProperties shares	Dec. 31, 2019 shares	Nov. 13, 2019 numberOfProperties	Jun. 30, 2019 shares	Mar. 31, 2019 shares	Dec. 31, 2018 shares
Organizational Structure [Line Items]
Number of real estate properties					7
Common stock, shares issued (in shares) | shares	184,814,924	184,814,924		185,302,037
Common stock, shares outstanding (in shares) | shares	184,814,924	184,814,924		185,302,037
Number of tenants with rent relief, COVID-19	2	2
Common Stock
Organizational Structure [Line Items]
Common stock, shares outstanding (in shares) | shares			185,228,220	185,302,037		185,871,023	186,188,796	186,464,794
KBS Capital Advisors LLC
Organizational Structure [Line Items]
Period of Advisory Agreement renewal		1 year
Period of termination notice		60 days
KBS Capital Advisors LLC |  Common Stock
Organizational Structure [Line Items]
Shares held by affiliate | shares	20,000	20,000
Office Properties
Organizational Structure [Line Items]
Number of real estate properties	4	4
Decrease in real estate property values, COVID-19 | $	$ (70.8)
Office Campus
Organizational Structure [Line Items]
Number of real estate properties	1	1	1
Office Buildings, Campus
Organizational Structure [Line Items]
Number of real estate properties	3	3
KBS Limited Partnership II
Organizational Structure [Line Items]
Partnership interest in Operating Partnership		0.10%
Partnership interest in the Operating Partnership and is its sole limited partner		99.90%