v3.26.1
Shareholders' Equity - Table of Actual Regulatory Capital Amounts and Ratios (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Trustmark Corporation [Member] | Common Equity Tier 1 Capital (to Risk Weighted Assets) [Member]    
Common Equity Tier One Risk Based Capital [Abstract]    
Actual Regulatory Capital Amount $ 1,835,118 $ 1,814,295
Actual Regulatory Capital Ratio 11.70% 11.72%
Minimum Regulatory Capital Required Ratio 7.00% 7.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio
Trustmark Corporation [Member] | Tier 1 Capital (to Risk Weighted Assets) [Member]    
Tier 1 Capital (to Risk Weighted Assets) [Abstract]    
Actual Regulatory Capital Amount $ 1,895,118 $ 1,874,295
Actual Regulatory Capital Ratio 12.09% 12.11%
Minimum Regulatory Capital Required Ratio 8.50% 8.50%
Minimum Regulatory Provision to be Well-Capitalized Ratio
Trustmark Corporation [Member] | Total Capital (to Risk Weighted Assets) [Member]    
Total Capital (to Risk Weighted Assets) [Abstract]    
Actual Regulatory Capital Amount $ 2,253,594 $ 2,231,283
Actual Regulatory Capital Ratio 14.37% 14.41%
Minimum Regulatory Capital Required Ratio 10.50% 10.50%
Minimum Regulatory Provision to be Well-Capitalized Ratio
Trustmark Corporation [Member] | Tier 1 Leverage (to Average Assets) [Member]    
Tier 1 Leverage (to Average Assets) [Abstract]    
Actual Regulatory Capital Amount $ 1,895,118 $ 1,874,295
Actual Regulatory Capital Ratio 10.19% 10.18%
Minimum Regulatory Capital Required Ratio 4.00% 4.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio
Trustmark Bank [Member] | Common Equity Tier 1 Capital (to Risk Weighted Assets) [Member]    
Common Equity Tier One Risk Based Capital [Abstract]    
Actual Regulatory Capital Amount $ 1,923,825 $ 1,908,101
Actual Regulatory Capital Ratio 12.27% 12.33%
Minimum Regulatory Capital Required Ratio 7.00% 7.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio 6.50% 6.50%
Trustmark Bank [Member] | Tier 1 Capital (to Risk Weighted Assets) [Member]    
Tier 1 Capital (to Risk Weighted Assets) [Abstract]    
Actual Regulatory Capital Amount $ 1,923,825 $ 1,908,101
Actual Regulatory Capital Ratio 12.27% 12.33%
Minimum Regulatory Capital Required Ratio 8.50% 8.50%
Minimum Regulatory Provision to be Well-Capitalized Ratio 8.00% 8.00%
Trustmark Bank [Member] | Total Capital (to Risk Weighted Assets) [Member]    
Total Capital (to Risk Weighted Assets) [Abstract]    
Actual Regulatory Capital Amount $ 2,110,259 $ 2,093,123
Actual Regulatory Capital Ratio 13.46% 13.52%
Minimum Regulatory Capital Required Ratio 10.50% 10.50%
Minimum Regulatory Provision to be Well-Capitalized Ratio 10.00% 10.00%
Trustmark Bank [Member] | Tier 1 Leverage (to Average Assets) [Member]    
Tier 1 Leverage (to Average Assets) [Abstract]    
Actual Regulatory Capital Amount $ 1,923,825 $ 1,908,101
Actual Regulatory Capital Ratio 10.35% 10.37%
Minimum Regulatory Capital Required Ratio 4.00% 4.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio 5.00% 5.00%