v3.26.1
LHFI and ACL, LHFI - Summary of Trustmark's Portfolio Segments, Loan Classes, Loan Pools and the ACL Methodology and Loss Drivers (Details)
3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | 1 -4 Family Residential Construction [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1] BBB 7-10 US CBI, National HPI (1) BBB 7-10 US CBI, National HPI (1)
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Lots and Development [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1] National HPI, Southern Unemployment (1) National HPI, Southern Unemployment (1)
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Unimproved Land [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1] National HPI, Southern Unemployment (1) National HPI, Southern Unemployment (1)
Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | All Other Consumer [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1],[2] BBB 7-10 US CBI (2), Southern Unemployment (1) BBB 7-10 US CBI (2), Southern Unemployment (1)
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | All Other Consumer [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1],[2] BBB 7-10 US CBI (2), Southern Unemployment (1) BBB 7-10 US CBI (2), Southern Unemployment (1)
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Consumer 1-4 Family - 1st Liens [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers National HPI, Southern Unemployment National HPI, Southern Unemployment
Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Nonresidential Owner- Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3] Southern Unemployment, BBB 7-10 US CBI (4) Southern Unemployment, BBB 7-10 US CBI (4)
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonresidential Owner- Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3] BBB 7-10 US CBI (4), Southern Unemployment BBB 7-10 US CBI (4), Southern Unemployment
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied - Hotel/Motel [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied - Office [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied- Retail [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-Occupied- Senior Living/ Nursing Homes [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Nonowner-occupied - All Other [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonresidential Owner- Occupied [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3] BBB 7-10 US CBI (4), Southern Unemployment BBB 7-10 US CBI (4), Southern Unemployment
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonowner-occupied - All Other [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Nonresidential Nonowner- Occupied - Apartments [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3],[4] BBB 7-10 US CBI (4), National Unemployment (5) BBB 7-10 US CBI (4), National Unemployment (5)
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Commercial and Industrial - Non-Working Capital [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers Trustmark historical data Trustmark historical data
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Commercial and Industrial - Working Capital [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers Trustmark historical data Trustmark historical data
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Equipment Finance Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology WARM WARM
Loss Drivers [5] Southern Unemployment, BBB 7-10 US CBI (3) Southern Unemployment, BBB 7-10 US CBI (3)
Commercial and Industrial Loans [Member] | Commercial and Industrial Loans [Member] | Credit Cards [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology WARM WARM
Loss Drivers Trustmark call report data Trustmark call report data
Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Other Construction [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [3] National Unemployment, BBB 7-10 US CBI, (4) National Unemployment, BBB 7-10 US CBI, (4)
Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Trustmark Mortgage [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology WARM WARM
Loss Drivers [4] Southern Unemployment, National HPI (5) Southern Unemployment, National HPI (5)
Consumer Loans [Member] | Consumer Loans [Member] | All Other Consumer [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers [1],[2] BBB 7-10 US CBI (2), Southern Unemployment (1) BBB 7-10 US CBI (2), Southern Unemployment (1)
Consumer Loans [Member] | Consumer Loans [Member] | Credit Cards [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology WARM WARM
Loss Drivers Trustmark call report data Trustmark call report data
Consumer Loans [Member] | Consumer Loans [Member] | Overdrafts [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology Loss Rate Loss Rate
Loss Drivers Trustmark historical data Trustmark historical data
State and Other Political Subdivision Loans [Member] | State and Other Political Subdivision Loans [Member] | Obligations of State and Political Subdivisions [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers Moody's Bond Default Study Moody's Bond Default Study
Other Commercial Loans and Leases [Member] | Other Commercial Loans And Leases [Member] | Commercial and Industrial - Non-Working Capital [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers Trustmark historical data Trustmark historical data
Other Commercial Loans and Leases [Member] | Other Commercial Loans And Leases [Member] | Commercial and Industrial - Working Capital [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers Trustmark historical data Trustmark historical data
Other Commercial Loans and Leases [Member] | Other Commercial Loans And Leases [Member] | Equipment Finance Leases [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology WARM WARM
Loss Drivers [5] Southern Unemployment, BBB 7-10 US CBI (3) Southern Unemployment, BBB 7-10 US CBI (3)
Other Commercial Loans and Leases [Member] | Other Commercial Loans And Leases [Member] | Other Loans [Member]    
Financing Receivable Recorded Investment [Line Items]    
Methodology DCF DCF
Loss Drivers BBB 7-10 US CBI, Southern Unemployment BBB 7-10 US CBI, Southern Unemployment
[1]

(1) Loss driver was National Unemployment at December 31, 2025.

[2]

(2) Loss driver was National HPI at December 31, 2025.

[3]

(4) Loss driver was National CRE Price Index at December 31, 2025.

[4]

(5) Loss driver was Southern Unemployment at December 31, 2025.

[5]

(3) Loss driver was National GDP at December 31, 2025.