ORGANIZATION (Details) $ / shares in Units, $ in Thousands		12 Months Ended			55 Months Ended	166 Months Ended
	Oct. 03, 2014 USD ($) shares	Dec. 31, 2024 property shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	May 29, 2015 USD ($) shares	Dec. 31, 2024 USD ($) property shares	Jan. 26, 2010 $ / shares shares
Organizational Structure [Line Items]
Common stock, shares issued (in shares)		148,516,246	148,516,246			148,516,246
Private Placement
Organizational Structure [Line Items]
Issuance of common stock (in shares)	258,462
Issuance of common stock, value | $	$ 2,400
Office Building
Organizational Structure [Line Items]
Number of real estate properties | property		13				13
Mixed-use Office/Retail Property
Organizational Structure [Line Items]
Number of real estate properties | property		1				1
Common Stock
Organizational Structure [Line Items]
Issuance of common stock (in shares)			1,900,374	3,434,632	169,006,162
Issuance of common stock, value | $			$ 19	$ 34	$ 1,700,000
Shares of common stock sold under dividend reinvestment plan (in shares)						46,154,757
Shares of common stock sold under dividend reinvestment plan, value | $						$ 471,300
Redemptions of common stock (in shares)			1,349,082	8,620,444		74,644,349
Redemptions of common stock, value | $			$ 14	$ 86		$ 789,200
KBS Capital Advisors LLC
Organizational Structure [Line Items]
Common stock, shares issued (in shares)							20,000
Common stock, purchase price per share (in dollars per share) | $ / shares							$ 10.00
KBS Capital Advisors LLC | Common Stock
Organizational Structure [Line Items]
Shares held by affiliate (in shares)		20,857				20,857
Operating Partnership
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%