XML 136 R121.htm IDEA: XBRL DOCUMENT v3.25.4
Defined Benefit and Other Postretirement Benefits - Additional Information (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2026
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions   $ 98    
Trustmark's contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions   109    
Estimated future benefit payments [Abstract]        
Accumulated other comprehensive income (loss) expected to be recognized during next fiscal year as components of net periodic benefit cost   317    
Pension Plan [Member] | Forecast        
Defined Benefit Plan Disclosure [Line Items]        
Trustmark's minimum required contribution to the Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions $ 91      
Supplemental Retirement Plan [Member]        
Estimated future benefit payments [Abstract]        
Accumulated other comprehensive income (loss) expected to be recognized during next fiscal year as components of net periodic benefit cost   14    
Defined Contribution Plan [Member]        
Other Benefit Plans - Defined Contribution Plan [Abstract]        
Trustmarks contribution to defined contribution plan   $ 10,400 $ 10,700 $ 10,800
Contributions up to a maximum of eligible compensation   6.00%    
Automatically enrolled Contributions of eligible compensation   3.00%    
Trustmark contributions to the plan   100.00%    
Period when associates may become eligible to make elective deferral contributions after employment   60 days