v3.26.1
FAIR VALUE MEASUREMENTS (Details) - EBP 002 - USD ($)
Dec. 31, 2025
Dec. 31, 2024
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 77,346,738 $ 65,683,914
Mutual Funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 13,922,485 12,699,152
Southside Bancshares, Inc. Common Stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 3,488,490 3,494,096
Collective Investment Trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 52,073,092 42,446,588
Pooled Separate Accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 7,862,671 7,044,078
Level 1    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 77,346,738 65,683,914
Level 1 | Mutual Funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 13,922,485 12,699,152
Level 1 | Southside Bancshares, Inc. Common Stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 3,488,490 3,494,096
Level 1 | Collective Investment Trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 52,073,092 42,446,588
Level 1 | Pooled Separate Accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 7,862,671 7,044,078
Level 2    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Mutual Funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Southside Bancshares, Inc. Common Stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Collective Investment Trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 2 | Pooled Separate Accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Mutual Funds    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Southside Bancshares, Inc. Common Stock    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Collective Investment Trusts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value 0 0
Level 3 | Pooled Separate Accounts    
EBP, Investment, Fair Value and NAV [Line Items]    
Investments, at fair value $ 0 $ 0