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v2.4.1.9

Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (6) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 Scale Factor Loan | Dec. 31, 2013 | Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | $ 66,448 us-gaap_LoansAndLeasesReceivableAllowance | $ 78,738 us-gaap_LoansAndLeasesReceivableAllowance | $ 89,518 us-gaap_LoansAndLeasesReceivableAllowance
Loans charged-off | (13,226)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (13,478)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (31,376)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Recoveries | 15,183 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 14,609 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 13,830 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery
Net recoveries (charge-offs) | 1,957 us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease | 1,131 us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease | (17,546)us-gaap_FinancingReceivableAllowanceForCreditLossesPeriodIncreaseDecrease
Provision for loan losses, LHFI | 1,211 trmk_ProvisionForLoanLossesLoansHeldForSale | (13,421)trmk_ProvisionForLoanLossesLoansHeldForSale | 6,766 trmk_ProvisionForLoanLossesLoansHeldForSale
Balance at end of period | 69,616 us-gaap_LoansAndLeasesReceivableAllowance | 66,448 us-gaap_LoansAndLeasesReceivableAllowance | 78,738 us-gaap_LoansAndLeasesReceivableAllowance
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Total | 69,616 us-gaap_LoansAndLeasesReceivableAllowance | 66,448 us-gaap_LoansAndLeasesReceivableAllowance | 78,738 us-gaap_LoansAndLeasesReceivableAllowance
Number of Loan Types For Commercial Portfolio | 9 trmk_NumberOfLoanTypesForCommercialPortfolio |  |
Maximum value of commercial LHFI which were subject to further refinement of allowance for loan loss methodology | 500 trmk_MaximumValueOfCommercialLHFIWhichWereSubjectToFurtherRefinementOfAllowanceForLoanLossMethodology |  |
Number Of Unique Qualitative Factors Used To Analyze Consumer Loans | 5 trmk_NumberOfUniqueQualitativeFactorsUsedToAnalyzeConsumerLoans |  |
Number of Risk Rate Factors For Commercial Loans | 450 trmk_NumberOfRiskRateTypesForCommercialPortfolio |  |
The Minimum Score For Qualitative Risk Factor | 0 trmk_QualitativeRiskFactorScoreRangeMinimum |  |
The Maximum Score For Qualitative Risk Factor | 100 trmk_QualitativeRiskFactorScoreRangeMaximum |  |
Additional provision due to revision of methodology | 2,222 us-gaap_FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod | 1,600 us-gaap_FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod | 1,400 us-gaap_FinancingReceivableAllowanceForCreditLossesEffectOfChangeInMethod
Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 66,448 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 78,738 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (13,226)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (13,478)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 15,183 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 14,609 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | 1,211 trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (13,421)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 69,616 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 66,448 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 12,764 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 5,181 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 56,852 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 61,267 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 69,616 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 66,448 us-gaap_LoansAndLeasesReceivableAllowance / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Real Estate Secured Financing Receivable [Member] | Construction, Land Development and Other Land [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 13,165 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 21,838 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (1,100)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (1,441)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 3,608 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,077 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | (2,600)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (10,309)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 13,073 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 13,165 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 2,767 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 988 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 10,306 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 12,177 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 13,073 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 13,165 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 9,633 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 12,957 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (2,505)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (1,298)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 922 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 427 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | 1,627 trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (2,453)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 9,677 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 9,633 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 450 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 191 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 9,227 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 9,442 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 9,677 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 9,633 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 19,672 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 21,096 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (390)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (1,002)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 944 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 225 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | (1,703)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (647)trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 18,523 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 19,672 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 2,787 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,307 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 15,736 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 17,365 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 18,523 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 19,672 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Real Estate Secured Financing Receivable [Member] | Other Loans Secured by Real Estate [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 2,080 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,197 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (277)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (910)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 229 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | 338 trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 564 trmk_ProvisionForLoanLossesLoansHeldForSale / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 2,141 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,080 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 52 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 123 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 2,089 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 1,957 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 2,141 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,080 us-gaap_LoansAndLeasesReceivableAllowance / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Commercial And Industrial Loans [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 15,522 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 14,319 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (2,092)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (1,371)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 2,657 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,298 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | 3,830 trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 276 trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 19,917 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 15,522 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 6,449 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 1,253 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 13,468 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 14,269 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 19,917 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 15,522 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Consumer Loans [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 2,405 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,087 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (1,965)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (2,425)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 3,883 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 4,798 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | (2,174)trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (3,055)trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 2,149 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,405 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 0 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 2,149 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,403 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | 2,149 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,405 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Other Loans [Member] | Allowance for Loan Loses, LHFI [Member] |  |  |
Financing Receivable, Allowance for Credit Losses [Roll Forward] |  |  |
Balance at beginning of period | 3,971 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,244 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Loans charged-off | (4,897)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | (5,031)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Recoveries | 3,169 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,555 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Provision for loan losses, LHFI | 1,893 trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 2,203 trmk_ProvisionForLoanLossesLoansHeldForSale / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Balance at end of period | 4,136 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,971 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract] |  |  |
Individually | 259 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 317 us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1 / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Collectively | 3,877 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | 3,654 us-gaap_FinancingReceivableAllowanceForCreditLossesCollectivelyEvaluatedForImpairment / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |
Total | $ 4,136 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember | $ 3,971 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / trmk_SubCategoryLoanLossAllowanceLhfiAxis = trmk_AllowanceForLoanLosesLhfiMember |

X
- Definition Maximum value of commercial LHFI which were subject to further refinement of allowance for loan loss methodology. + References No definition available. + Details
Name: | trmk_MaximumValueOfCommercialLHFIWhichWereSubjectToFurtherRefinementOfAllowanceForLoanLossMethodology
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of unique loan types the commercial portfolio was delineated into for analysis of loan loss allowance. + References No definition available. + Details
Name: | trmk_NumberOfLoanTypesForCommercialPortfolio
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of risk rate factors utilized for the commercial portfolio. + References No definition available. + Details
Name: | trmk_NumberOfRiskRateTypesForCommercialPortfolio
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of unique qualitative factors used to evaluate the consumer loan portfolio for loan loss allowance. + References No definition available. + Details
Name: | trmk_NumberOfUniqueQualitativeFactorsUsedToAnalyzeConsumerLoans
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The provision for loan losses on loans held-for-sale. + References No definition available. + Details
Name: | trmk_ProvisionForLoanLossesLoansHeldForSale
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition When presenting a range of scores, the highest potential score under the assessment procedure. + References No definition available. + Details
Name: | trmk_QualitativeRiskFactorScoreRangeMaximum
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition When presenting a range of scores, the lowest potential score under the assessment procedure. + References No definition available. + Details
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- Definition Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524 + Details
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- Definition Amount of direct write-downs of financing receivables charged against the allowance. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 11B -Subparagraph (c)(3) -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953423-111524 + Details
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