v3.26.1
Document and Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Aug. 14, 2026
Document and Entity Information    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Securities Act File Number 000-56852  
Entity Registrant Name PSB Financial, Inc.  
Entity Incorporation, State or Country Code MD  
Entity Tax Identification Number 39-4296886  
Entity Address, Address Line One 202 North Main Street  
Entity Address, Address Line Two P.O. Box 191  
Entity Address, City or Town Deer Lodge  
Entity Address, State or Province MT  
Entity Address, Postal Zip Code 59722  
City Area Code 406  
Local Phone Number 846-2202  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   1,719,250
Entity Central Index Key 0002087419  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false