v3.25.1
Cover Page - shares
3 Months Ended
Mar. 31, 2025
May 08, 2025
Cover [Abstract]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2025  
Document Transition Report false  
Entity File Number 000-54687  
Entity Registrant Name KBS REAL ESTATE INVESTMENT TRUST III, INC.  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 27-1627696  
Entity Address, Address Line One 800 Newport Center Drive, Suite 700  
Entity Address, City or Town Newport Beach,  
Entity Address, State or Province CA  
Entity Address, Postal Zip Code 92660  
City Area Code 949  
Local Phone Number 417-6500  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   148,516,246
Amendment flag false  
Document fiscal period focus Q1  
Entity Central Index Key 0001482430  
Document Fiscal Year Focus 2025  
Current Fiscal Year End Date --12-31