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Loans Held for Investment (LHFI) and Allowance for Loan Losses, LHFI (4) (Details) (USD $) | 12 Months Ended |
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Dec. 31, 2014 CreditRiskGrade KeyRatios Loan | Dec. 31, 2013
Financing Receivable Aging [Abstract] |  |
Current | $ 6,349,071,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent | $ 5,714,900,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent
Nonaccrual | 79,343,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus | 65,238,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Total LHFI | 6,449,469,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome | 5,798,881,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Credit amount used as baseline in evaluating residential real estate development and non-owner occupied commercial real estate for loan policy | 1,000,000 trmk_CreditAmountUsedBaselineEvaluationResidentialRealEstateDevelopmentAndNonOwnerOccupiedCommercialRealEstate |
Number of days used as baseline in evaluating collateral documentation exceptions for loan policy (in days) | 90 days |
Loan amount used as baseline in credit quality review for loan policy | 100,000 trmk_LoanAmountUsedBaselineCreditQualityReviewForLoanPolicy |
Number of key quality ratios | 6 trmk_NumberOfKeyQualityRatios |
Number of individual credit risk grades | 10 trmk_NumberOfIndividualCreditRiskGrades |
Number of primary commercial loan groups | 9 trmk_NumberOfPrimaryCommercialLoanGroups |
Minimum [Member] |  |
Financing Receivable Aging [Abstract] |  |
Period to conduct asset review | 6 months |
Maximum [Member] |  |
Financing Receivable Aging [Abstract] |  |
Period to conduct asset review | 18 months |
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 605,685,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 582,639,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 13,867,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 13,327,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 619,877,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 596,889,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 1,595,557,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,451,528,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 25,621,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 21,603,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 1,634,397,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,485,564,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 1,525,482,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,391,286,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 25,717,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 21,809,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 1,553,193,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,415,139,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 252,389,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 188,030,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 1,318,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,327,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 253,787,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 189,362,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Consumer Loans [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 165,503,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 162,843,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Nonaccrual | 88,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 151,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Total LHFI | 167,964,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 165,308,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Other Loans [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 949,132,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 788,253,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Nonaccrual | 628,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 735,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Total LHFI | 949,901,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 789,005,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Commercial Portfolio Segment [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 4,708,378,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember | 4,213,735,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember
Commercial Portfolio Segment [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 4,519,970,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 3,982,761,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 22,663,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 36,313,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 164,053,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 190,743,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,692,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 3,918,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 556,641,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 545,691,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 518,944,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 493,380,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 479,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 4,383,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 37,022,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 47,610,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 196,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 318,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 134,551,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 128,068,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 125,203,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 119,640,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,652,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 479,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 7,483,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 7,839,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 213,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 110,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,552,318,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,413,692,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,462,226,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 1,313,470,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 8,431,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 12,620,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 81,661,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 87,203,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 399,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 251,380,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 185,942,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 246,099,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 178,951,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 306,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 4,975,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 6,756,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 235,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Commercial and Industrial Loans [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,270,344,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 1,157,596,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Commercial Portfolio Segment [Member] | Commercial and Industrial Loans [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 1,239,247,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 1,099,429,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Commercial and Industrial Loans [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 4,245,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 18,771,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Commercial and Industrial Loans [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 26,133,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 37,209,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Commercial and Industrial Loans [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 719,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 2,187,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Consumer Loans [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 496,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Commercial Portfolio Segment [Member] | Consumer Loans [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 496,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Consumer Loans [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Consumer Loans [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Consumer Loans [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 0 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Commercial Portfolio Segment [Member] | Other Loans [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 943,144,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 782,250,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Commercial Portfolio Segment [Member] | Other Loans [Member] | Pass [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 928,251,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | 777,395,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember
Commercial Portfolio Segment [Member] | Other Loans [Member] | Special Mention [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 7,550,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | 60,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember
Commercial Portfolio Segment [Member] | Other Loans [Member] | Substandard [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 6,779,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | 4,126,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember
Commercial Portfolio Segment [Member] | Other Loans [Member] | Doubtful [Member] |  |
Financing Receivable [Abstract] |  |
Financing receivable commercial | 564,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | 669,000 us-gaap_LoansReceivableCommercialTradeFinancing / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember
Consumer Portfolio Segment [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 1,703,795,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,552,447,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Past Due 30 - 89 Days | 12,795,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 11,095,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Past Due Greater Than 90 Days | 2,638,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 3,298,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Nonaccrual | 21,863,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 18,306,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Subtotal | 1,741,091,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 1,585,146,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Total LHFI | 6,449,469,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember | 5,798,881,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember
Consumer Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 62,897,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 50,850,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due 30 - 89 Days | 199,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 131,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due Greater Than 90 Days | 59,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 81,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 217,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Subtotal | 63,236,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 51,198,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 619,877,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 596,889,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Consumer Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 1,465,355,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,327,624,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due 30 - 89 Days | 10,429,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 8,937,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due Greater Than 90 Days | 2,367,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 2,996,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 21,695,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 17,939,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Subtotal | 1,499,846,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,357,496,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 1,634,397,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,485,564,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Consumer Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Nonfarm, Nonresidential Properties [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 875,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,439,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due 30 - 89 Days | 0 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 8,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due Greater Than 90 Days | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Subtotal | 875,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,447,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 1,553,193,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 1,415,139,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Consumer Portfolio Segment [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured Financing Receivable [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 2,407,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 3,418,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due 30 - 89 Days | 0 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 2,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Past Due Greater Than 90 Days | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Nonaccrual | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Subtotal | 2,407,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 3,420,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Total LHFI | 253,787,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | 189,362,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember
Consumer Portfolio Segment [Member] | Commercial and Industrial Loans [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 0 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 13,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Past Due 30 - 89 Days | 5,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 5,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Past Due Greater Than 90 Days | 1,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Nonaccrual | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Subtotal | 6,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 18,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Total LHFI | 1,270,350,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | 1,157,614,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember
Consumer Portfolio Segment [Member] | Consumer Loans [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 165,504,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 162,348,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Past Due 30 - 89 Days | 2,162,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 2,012,000 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Past Due Greater Than 90 Days | 211,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 302,000 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Nonaccrual | 87,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 150,000 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Subtotal | 167,964,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 164,812,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Total LHFI | 167,964,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | 165,308,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember
Consumer Portfolio Segment [Member] | Other Loans [Member] |  |
Financing Receivable Aging [Abstract] |  |
Current | 6,757,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 6,755,000 us-gaap_FinancingReceivableRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Past Due 30 - 89 Days | 0 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Past Due Greater Than 90 Days | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 0 trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Nonaccrual | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 0 us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Subtotal | 6,757,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | 6,755,000 trmk_ConsumerLoansFinancingReceivableRecordedInvestment / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember
Total LHFI | $ 949,901,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | $ 789,005,000 us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember

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- Definition Recorded Investment in financing receivables categorized as consumer loans including those current, past due and nonaccrual status. + References No definition available. + Details
Name: | trmk_ConsumerLoansFinancingReceivableRecordedInvestment
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition The minimum credit amount used to determine which residential real estate and non-owner occupied commercial real estate projects are evaluated under credit quality reviews by entity. + References No definition available. + Details
Name: | trmk_CreditAmountUsedBaselineEvaluationResidentialRealEstateDevelopmentAndNonOwnerOccupiedCommercialRealEstate
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | trmk_FinancingReceivableAbstract
Namespace Prefix: | trmk_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Financing receivables that are less than 60 days past due but more than 29 days past due. + References No definition available. + Details
Name: | trmk_FinancingReceivableRecordedInvestment30To89DaysPastDue
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Financing receivables that are greater than 90 days past due. + References No definition available. + Details
Name: | trmk_FinancingReceivableRecordedInvestmentGreaterThan90DaysPastDue
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The minimum baseline dollar amount used to evaluate loans that are either delinquent or on nonaccrual under the entity's credit quality review process. + References No definition available. + Details
Name: | trmk_LoanAmountUsedBaselineCreditQualityReviewForLoanPolicy
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition The minimum of days past due used as a baseline for the evaluation of collateral documentation under the entity's loan policy. + References No definition available. + Details
Name: | trmk_NumberOfDaysPastDueUsedInEvaluatingCollateralExceptions
Namespace Prefix: | trmk_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition This line item represents the number of individual credit risk grades established by the entity. + References No definition available. + Details
Name: | trmk_NumberOfIndividualCreditRiskGrades
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition This line item represents the number of key quality ratios on which entity's loan portfolio credit quality indicators focused. + References No definition available. + Details
Name: | trmk_NumberOfKeyQualityRatios
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition This line item represents the number of primary commercial loan groups. + References No definition available. + Details
Name: | trmk_NumberOfPrimaryCommercialLoanGroups
Namespace Prefix: | trmk_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition This line item represents the period to conduct asset review by the entity. + References No definition available. + Details
Name: | trmk_PeriodToConductAssetReview
Namespace Prefix: | trmk_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentAgingAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Financing receivables that are current. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953401-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5111-111524 + Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5074-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522 + Details
Name: | us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Amount before allowance of commercial loans, including, but not limited to, letters of credit, bankers' acceptances, receivables factoring, open account financing, for international trade activities. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5066-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph a -Article 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(a)(7)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
Name: | us-gaap_LoansReceivableCommercialTradeFinancing
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | trmk_FinancingReceivableByPortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | trmk_FinancingReceivableByPortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=trmk_ConsumerLoansFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=trmk_OtherLoansFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=trmk_RealEstateSecuredFinancingReceivableMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |