Derivative Financial Instruments - Effects of Derivative Instruments on Statements of Operations (Details) - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Designated as Hedging Instrument [Member] | ||||
| Derivatives, Fair Value [Line Items] | ||||
| Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) and recognized in interest and fees on LHFS and LHFI | $ (805) | $ (2,681) | $ (1,740) | $ (5,361) |
| Derivatives not Designated as Hedging Instruments [Member] | Location, Statement of Income, Balance [Axis]: trmk:BankCardAndOtherFees | ||||
| Derivatives, Fair Value [Line Items] | ||||
| Amount of gain (loss) recognized in bank card and other fees | 195 | 452 | 565 | 364 |
| Derivatives not Designated as Hedging Instruments [Member] | Location, Statement of Income, Balance [Axis]: trmk:MortgageBankingIncome | ||||
| Derivatives, Fair Value [Line Items] | ||||
| Amount of gain (loss) recognized in mortgage banking, net | $ (4,551) | $ 1,842 | $ (6,859) | $ 6,557 |