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Acquired Loans Part 5 (Details) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
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Acquired Loans, Aging [Abstract] |  |  |  |
Current | $ 498,236 trmk_AcquiredLoansRecordedInvestmentCurrent |  | $ 718,638 trmk_AcquiredLoansRecordedInvestmentCurrent |
Past Due Greater Than 90 Days | 43,412 trmk_AcquiredLoansMoreThan90DaysPastDue | [1] | 63,444 trmk_AcquiredLoansMoreThan90DaysPastDue | [1]
Nonaccrual | 1,144 trmk_AcquiredLoansNonaccrualStatus | [2] | 2,353 trmk_AcquiredLoansNonaccrualStatus | [2]
Total acquired loans | 549,409 trmk_AcquiredLoansCarryingValueLoans |  | 804,206 trmk_AcquiredLoansCarryingValueLoans |
Percentage of risk of losses incurred on acquired covered loans (in hundredths) | 20.00%trmk_PercentageOfRiskOfLossesIncurredOnAcquiredLoans |  | 20.00%trmk_PercentageOfRiskOfLossesIncurredOnAcquiredLoans |
Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 477,216 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 691,632 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Past Due Greater Than 90 Days | 42,149 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember | [1] | 60,308 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember | [1]
Nonaccrual | 1,077 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember | [2] | 1,867 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember | [2]
Total acquired loans | 525,783 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 769,990 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 21,020 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember |  | 27,006 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember |
Past Due Greater Than 90 Days | 1,263 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [1] | 3,136 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [1]
Nonaccrual | 67 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [2] | 486 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [2]
Total acquired loans | 23,626 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember |  | 34,216 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember |
Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 35,877 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 65,001 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 21,985 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 31,744 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 194 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 67 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 58,309 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 98,928 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 821 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 1,278 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 376 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 553 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 445 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 1,197 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 2,363 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 107,779 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 145,142 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 5,162 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 7,589 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 422 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 116 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 116,920 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 157,914 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 12,154 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 14,401 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 477 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 1,142 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 13,180 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 16,416 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 188,094 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 263,276 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 13,275 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 15,421 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 461 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 202,323 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 287,136 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 6,945 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 8,247 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 793 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 7,672 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 10,945 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 27,209 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 31,953 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 604 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 1,922 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 33 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 27,813 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 33,948 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 728 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 1,932 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 368 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1] | 2 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [2]
Total acquired loans | 1,096 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 2,644 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Commercial And Industrial Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 86,234 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 144,195 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 1,099 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [1] | 3,387 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [1]
Nonaccrual | 461 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [2] | 1,170 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [2]
Total acquired loans | 88,256 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 149,495 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Commercial And Industrial Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 168 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 340 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 42 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [1] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [1]
Nonaccrual | 67 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [2] | 41 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [2]
Total acquired loans | 277 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 394 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Consumer Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 9,633 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 18,097 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 24 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [1] | 92 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [2]
Total acquired loans | 9,772 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 18,428 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Consumer Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 119 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [1] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [2]
Total acquired loans | 0 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 119 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Other Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 22,390 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 23,968 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [1] | 153 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [2] | 20 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [2]
Total acquired loans | 22,390 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 24,141 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Other Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 204 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 689 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [1] | 646 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [1]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [2] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [2]
Total acquired loans | 204 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 1,335 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Commercial Portfolio Segment [Member] | Pass [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 320,915 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 433,015 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 315,953 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 424,355 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 4,962 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 8,660 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Special Mention [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 5,101 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 18,902 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 4,646 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 18,201 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 455 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 701 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Substandard [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 108,813 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 186,787 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 103,400 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 177,897 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 5,413 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 8,890 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Doubtful [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 11,931 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 22,494 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 11,827 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 21,075 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 104 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 1,419 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Commercial Subtotal [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 446,760 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 661,198 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 435,826 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 641,528 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 10,934 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 19,670 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 20,224 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 39,075 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 228 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 280 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 2,506 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 28,339 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 42,486 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 955 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 1,126 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 5,821 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 8,445 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 102 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 771 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 54,664 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 92,512 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 1,057 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 2,125 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 30,796 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 33,810 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 194 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 1,629 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 760 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 2,983 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 235 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 430 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 8,466 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 17,422 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 1,045 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 1,798 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 388 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 538 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 40,410 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 54,753 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 1,474 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 3,857 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 157,753 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 184,594 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 4,419 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 5,446 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 3,452 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 9,027 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 88 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 109 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 39,408 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 88,952 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 2,879 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 4,723 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 1,710 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 4,563 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 202,323 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 287,136 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 7,386 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 10,278 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 22,754 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 28,156 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 832 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 92 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 1,437 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 108 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 134 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 4,864 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 4,071 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 426 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 717 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 95 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 184 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 2 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 2 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 27,805 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 33,848 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 536 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 1,685 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 64,720 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 116,818 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 145 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 254 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 17 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 2,248 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 24 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 28 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 19,706 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 24,084 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 108 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 112 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 3,813 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 6,039 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 88,256 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 149,189 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 277 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 394 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 21 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 21 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Pass [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 19,706 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |  | 21,881 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember |
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Pass [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 204 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3] | 271 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_PassMember | [3]
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Special Mention [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 45 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |  | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember |
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Special Mention [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3] | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SpecialMentionMember | [3]
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Substandard [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 2,617 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |  | 882 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember |
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Substandard [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3] | 414 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_SubstandardMember | [3]
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Doubtful [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |  | 1,306 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember |
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Doubtful [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 0 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3] | 646 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = us-gaap_DoubtfulMember | [3]
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 22,368 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |  | 24,069 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember |
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Commercial Subtotal [Member] | Covered [Member] |  |  |  |
Acquired Loans, Commercial Loans [Abstract] |  |  |  |
Acquired loans | 204 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3] | 1,331 trmk_AcquiredLoansCarryingValue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_CommercialPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember / us-gaap_InternalCreditAssessmentAxis = trmk_CommercialSubtotalMember | [3]
Consumer Portfolio Segment [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 96,194 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 132,901 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Past Due 30-89 Days | 2,947 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 4,793 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Past Due Greater Than 90 Days | 3,391 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 5,205 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Nonaccrual | 117 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 109 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Subtotal | 102,649 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 143,008 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Total acquired loans | 549,409 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |  | 804,206 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember |
Consumer Portfolio Segment [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 84,318 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 120,354 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Past Due 30-89 Days | 2,474 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 3,946 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Past Due Greater Than 90 Days | 3,048 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 4,053 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Nonaccrual | 117 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 109 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Subtotal | 89,957 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 128,462 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Total acquired loans | 525,783 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |  | 769,990 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember |
Consumer Portfolio Segment [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 11,876 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 12,547 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Past Due 30-89 Days | 473 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 847 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Past Due Greater Than 90 Days | 343 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 1,152 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Subtotal | 12,692 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 14,546 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Total acquired loans | 23,626 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3] | 34,216 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember | [3]
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 3,338 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 5,813 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due 30-89 Days | 25 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 108 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 282 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 495 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Subtotal | 3,645 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 6,416 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Total acquired loans | 58,309 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 98,928 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 140 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 133 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 77 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 28 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Subtotal | 140 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 238 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Total acquired loans | 1,197 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 2,363 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 71,316 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 95,987 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due 30-89 Days | 2,335 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 3,599 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 2,742 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 3,466 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Nonaccrual | 117 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 109 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Subtotal | 76,510 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 103,161 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Total acquired loans | 116,920 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 157,914 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Secured by 1-4 Family Residential Properties [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 10,925 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 11,179 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due 30-89 Days | 473 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 428 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 308 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 952 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Subtotal | 11,706 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 12,559 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Total acquired loans | 13,180 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 16,416 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_ResidentialFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Subtotal | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Total acquired loans | 202,323 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 287,136 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonfarm, Nonresidential Properties [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 286 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 495 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 172 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Subtotal | 286 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 667 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Total acquired loans | 7,672 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 10,945 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_NonresidentialPropertiesFinancingReceivablesMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 8 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 100 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Subtotal | 8 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 100 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Total acquired loans | 27,813 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |  | 33,948 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 525 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 617 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 342 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 35 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Subtotal | 560 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 959 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Total acquired loans | 1,096 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3] | 2,644 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableBySubClassReceivableAxis = trmk_OtherRealEstateSecuredFinancingReceivableMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_RealEstateSecuredFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 306 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Subtotal | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 306 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Total acquired loans | 88,256 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |  | 149,495 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Subtotal | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Total acquired loans | 277 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3] | 394 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_CommercialAndIndustrialLoansFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 9,634 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 18,076 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Past Due 30-89 Days | 114 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 239 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 24 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 92 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Subtotal | 9,772 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 18,407 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Total acquired loans | 9,772 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |  | 18,428 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 119 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Subtotal | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 119 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Total acquired loans | 0 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3] | 119 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_ConsumerLoansFinancingReceivableMember | [3]
Consumer Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Noncovered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 22 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 72 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Subtotal | 22 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 72 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Total acquired loans | 22,390 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |  | 24,141 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_NoncoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember |
Consumer Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Covered [Member] |  |  |  |
Acquired Loans, Aging [Abstract] |  |  |  |
Current | 0 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | 4 trmk_AcquiredLoansRecordedInvestmentCurrent / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
Past Due 30-89 Days | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoans30To89DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
Past Due Greater Than 90 Days | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansMoreThan90DaysPastDue / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
Nonaccrual | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | 0 trmk_AcquiredLoansNonaccrualStatus / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
Subtotal | 0 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | 4 trmk_AcquiredLoansCarryingValueSubtotal / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
Total acquired loans | $ 204 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3] | $ 1,335 trmk_AcquiredLoansCarryingValueLoans / trmk_FinancingReceivableByPortfolioSegmentAxis = us-gaap_ConsumerPortfolioSegmentMember / trmk_FinancingReceivableByTypeAxis = trmk_CoveredMember / us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis = trmk_OtherLoansFinancingReceivableMember | [3]
[1] | Past due 90 days or more but still accruing interest.
[2] | Acquired loans not accounted for under FASB ASC Topic 310-30.
[3] | Total dollar balances are presented in this table; however, these loans are covered by the loss-share agreement with the FDIC. TNB is at risk for only 20% of the losses incurred on these loans.

X
- Definition Acquired loans that are less than 90 days past due but more than 29 days past due. + References No definition available. + Details
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Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition The carrying value of acquired loans during the period. + References No definition available. + Details
Name: | trmk_AcquiredLoansCarryingValue
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying value of acquired loans during the period. + References No definition available. + Details
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Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The carrying value of acquired loans, subtotal of current and noncurrent. + References No definition available. + Details
Name: | trmk_AcquiredLoansCarryingValueSubtotal
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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- Definition Acquired loans more than 90 days past due. + References No definition available. + Details
Name: | trmk_AcquiredLoansMoreThan90DaysPastDue
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Acquired loans that are on nonaccrual status as of the balance sheet date. + References No definition available. + Details
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Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Acquired loans that are current. + References No definition available. + Details
Name: | trmk_AcquiredLoansRecordedInvestmentCurrent
Namespace Prefix: | trmk_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The percentage of risk of losses incurred on acquired covered loans. + References No definition available. + Details
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Namespace Prefix: | trmk_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- 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: |

X
- Details
Name: | trmk_FinancingReceivableByTypeAxis=trmk_CoveredMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | trmk_FinancingReceivableByTypeAxis=trmk_NoncoveredMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=trmk_CommercialAndIndustrialLoansFinancingReceivableMember
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: |