RELATED PARTY TRANSACTIONS - Additional Information (Details)							1 Months Ended	3 Months Ended
	Feb. 06, 2025	Dec. 20, 2024	Nov. 22, 2024 property	Aug. 12, 2024 USD ($) $ / ft²	Oct. 01, 2022 USD ($)	Jul. 18, 2019 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2026 USD ($)	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)	Oct. 11, 2024 USD ($)	Sep. 30, 2022 USD ($)	May 29, 2015 ft²
Related Party Transaction [Line Items]
Restricted cash								$ 30,318,000		$ 38,557,000
Payable as of								20,439,000		19,817,000
Rental income								$ 53,903,000	$ 60,264,000
KBS Capital Advisors LLC or Affiliates
Related Party Transaction [Line Items]
Selling commissions fees, percent of sales price								1.00%
KBS Capital Advisors LLC, Affiliates or Unaffiliated Third Parties | Maximum
Related Party Transaction [Line Items]
Selling commissions fees, percent of sales price								6.00%
Advisor and Dealer Manager
Related Party Transaction [Line Items]
Incurred costs (reimbursement)								$ 4,541,000	4,695,000
Advisor and Dealer Manager | Monthly asset management cash fee
Related Party Transaction [Line Items]
Incurred costs (reimbursement)					$ 1,150,000
Advisor and Dealer Manager | Fully funded bonus retention funded
Related Party Transaction [Line Items]
Incurred costs (reimbursement)							$ 8,500,000
Advisor and Dealer Manager | Bonus retention fund payments
Related Party Transaction [Line Items]
Incurred costs (reimbursement)								$ 0
Advisor and Dealer Manager | Deferred asset management fees
Related Party Transaction [Line Items]
Payable as of												$ 8,500,000
Advisor and Dealer Manager | Non compounded return on net invested capital
Related Party Transaction [Line Items]
Related party transaction rate (percent)								8.00%
Advisor and Dealer Manager | Asset management fees
Related Party Transaction [Line Items]
Incurred costs (reimbursement)								$ 4,155,000	4,584,000
Advisor and Dealer Manager | Disposition Fees
Related Party Transaction [Line Items]
Incurred costs (reimbursement)								322,000	0
Advisor and Dealer Manager | Incurred costs of supplemental coverage
Related Party Transaction [Line Items]
Incurred costs (reimbursement)								$ 0	0
SREIT
Related Party Transaction [Line Items]
Acquisition fee as percent of acquisition price of real estate						1.00%
Dividend fee as percent of sale price of real estate						0.50%
Development management fee as percent of total project cost						3.00%
SREIT | Linda Bren 2017 Trust
Related Party Transaction [Line Items]
Investment in an unconsolidated entity						$ 5,000,000.0
Modified Portfolio Revolving Loan Facility | Secured Debt
Related Party Transaction [Line Items]
Debt instrument, covenant, maximum asset management fee payment, percentage								0.90
Debt instrument, covenant, deferred asset management fee payment, percentage								0.10
Debt instrument, covenant, deferred asset disposition fees payment, percentage								0.0065
Amended and Restated Portfolio Loan Facility
Related Party Transaction [Line Items]
Debt instrument, covenant, deferred asset management fee payment, percentage	0.10
Carillon, 515 Congress, Gateway Tech Center, 201 17th Street, and Accenture Tower
Related Party Transaction [Line Items]
Debt instrument, covenant, maximum asset management fee payment, associated properties, number | property			5
Debt instrument, covenant, maximum asset management fee payment, percentage			0.90
Debt instrument, covenant, deferred asset management fee payment, percentage			0.10
515 Congress, Gateway Tech Center and 201 17th Street | Modified Portfolio Revolving Loan Facility | Secured Debt
Related Party Transaction [Line Items]
Debt instrument, covenant, maximum asset management fee payment, percentage								0.90
Debt instrument, covenant, deferred asset management fee payment, percentage								0.10
Debt instrument, covenant, deferred asset disposition fees payment, percentage								0.0065
Accenture Tower
Related Party Transaction [Line Items]
Debt instrument, covenant, deferred asset management fee payment, percentage		0.10
Related Party
Related Party Transaction [Line Items]
Monthly asset management fee, percent of acquisition expense, excluding acquisition fees related to thereto (percent)								0.0625%
Rental income								$ 70,000	$ 69,000
Related Party | Subsidiaries
Related Party Transaction [Line Items]
Net rentable area (in sq feet) | ft²													5,046
Total rentable square feet (percentage)													2.40%
Annualized base rent				$ 300,000
Average Annualized Base Rent per sq. ft. (usd per sqft) | $ / ft²				53.75
Related Party | Asset management fees
Related Party Transaction [Line Items]
Payable as of								1,300,000		1,300,000
Related Party | Advisor and Dealer Manager
Related Party Transaction [Line Items]
Payable as of								20,439,000		19,817,000
Related Party | Advisor and Dealer Manager | Bonus retention fund deposit
Related Party Transaction [Line Items]
Restricted cash								8,500,000
Payable as of								8,500,000		8,500,000
Related Party | Advisor and Dealer Manager | Deferred asset management fees
Related Party Transaction [Line Items]
Payable as of								$ 8,500,000		8,500,000
Related Party | Advisor and Dealer Manager | The renewal advisory agreement
Related Party Transaction [Line Items]
Renewal period								1 year
Termination period								60 days
Related Party | Advisor and Dealer Manager | Asset management fees
Related Party Transaction [Line Items]
Payable as of								$ 20,082,000		19,740,000
Related Party | Advisor and Dealer Manager | Asset Management Fees Deferred in Connection with Agreements Related to the Refinancing of the Company’s Debt Obligations
Related Party Transaction [Line Items]
Payable as of								1,800,000		1,400,000
Related Party | Advisor and Dealer Manager | Disposition Fees
Related Party Transaction [Line Items]
Payable as of								$ 322,000		$ 0	$ 500,000
Related Party | SREIT
Related Party Transaction [Line Items]
Annual base fee (percent)						10.00%
Annual performance fee (percent)						25.00%
Related Party | Carillon, 515 Congress, Gateway Tech Center, 201 17th Street, and Accenture Tower | Advisor and Dealer Manager | Disposition Fees
Related Party Transaction [Line Items]
Selling commissions fees maximum reduction, percent of sales price								0.0065
Related Party | Portfolio Loan Properties, Accenture Tower, The Almaden | Advisor and Dealer Manager | Disposition Fees
Related Party Transaction [Line Items]
Selling commissions fees maximum reduction, percent of sales price	0.0065