v3.26.1
Document and Entity Information - shares
3 Months Ended
Mar. 31, 2026
May 11, 2026
Cover [Abstract]    
Document Type 10-Q  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Registrant Name SECURITY MIDWEST BANCORP, INC.  
Entity Central Index Key 0002036060  
Current Fiscal Year End Date --12-31  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Common Stock, Shares Outstanding   889,781
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code MD  
Entity File Number 000-56767  
Entity Tax Identification Number 99-4917712  
Entity Address, Address Line One 510 E. Monroe  
Entity Address, City or Town Springfield  
Entity Address, State or Province IL  
Entity Address, Postal Zip Code 62701  
City Area Code 217  
Local Phone Number 789-3500  
Entity Shell Company false  
Title of 12(b) Security None  
Document Quarterly Report true  
Document Transition Report false