v3.26.1
Cover Page - shares
 6 Months Ended
Jun. 30, 2026
Jul. 21, 2026
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2026  
Document Transition Report false  
Entity File Number 001-42396  
Entity Registrant Name SOUTHSIDE BANCSHARES, INC.  
Entity Incorporation, State or Country Code TX  
Entity Tax Identification Number 75-1848732  
Entity Address, Address Line One 1201 S. Beckham Avenue,  
Entity Address, City or Town Tyler,  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 75701  
City Area Code 903  
Local Phone Number 531-7111  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   29,807,980
Entity Central Index Key 0000705432  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
Amendment Flag false  
New York Stock Exchange    
Document Information [Line Items]    
Title of 12(b) Security Common Stock, $1.25 par value  
Trading Symbol SBSI  
Security Exchange Name NYSE  
NYSE Texas    
Document Information [Line Items]    
Title of 12(b) Security Common Stock, $1.25 par value  
Trading Symbol SBSI  
Security Exchange Name NYSETX