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Shareholders' Equity - Table of Actual Regulatory Capital Amounts and Ratios (Details) - USD ($) $ in Thousands | Dec. 31, 2025 | Dec. 31, 2024
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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 | $ 1,814,295 | $ 1,729,672
Actual Regulatory Capital Ratio | 11.72% | 11.54%
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 | $ 1,874,295 | $ 1,789,672
Actual Regulatory Capital Ratio | 12.11% | 11.94%
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 | $ 2,231,283 | $ 2,094,874
Actual Regulatory Capital Ratio | 14.41% | 13.97%
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 | $ 1,874,295 | $ 1,789,672
Actual Regulatory Capital Ratio | 10.18% | 9.99%
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 | $ 1,908,101 | $ 1,828,044
Actual Regulatory Capital Ratio | 12.33% | 12.20%
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 | $ 1,908,101 | $ 1,828,044
Actual Regulatory Capital Ratio | 12.33% | 12.20%
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 | $ 2,093,123 | $ 2,009,544
Actual Regulatory Capital Ratio | 13.52% | 13.41%
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 | $ 1,908,101 | $ 1,828,044
Actual Regulatory Capital Ratio | 10.37% | 10.21%
Minimum Regulatory Capital Required Ratio | 4.00% | 4.00%
Minimum Regulatory Provision to be Well-Capitalized Ratio | 5.00% | 5.00%

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