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v3.25.2

LHFI and ACL, LHFI - Additional Information (Details 1) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2025 USD ($) Region | Dec. 31, 2024 USD ($)
Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract] |  |
Accrued interest receivable | $ | $ 63.6 | $ 64.7
Maximum concentration of loan as a percentage of total LHFI | 10.00% |
Key market regions | Region | 6 |

X
- Definition The maximum concentration for any loan concentration as a percentage of total loans held for investment. + References No definition available. + Details
Name: | trmk_ConcentrationRiskCreditRiskFinancialInstrumentMaximumExposurePercentage
Namespace Prefix: | trmk_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of key market regions the entity operates that are included in the qualitative reserve allocation review process. + References No definition available. + Details
Name: | trmk_KeyMarketRegionsInQualitativeReserveAllocation
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Loans and leases receivable, accrual of interest. + References No definition available. + Details
Name: | trmk_LoansAndLeasesReceivableAccrualOfInterest
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_AccountsNotesLoansAndFinancingReceivableGrossAllowanceAndNetAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration