Fair Value - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Outstanding balances in collateral dependent related to allowance for credit losses	$ 42,900		$ 49,100
Collateral dependent related to allowance for credit losses	12,600		12,400
Foreclosed assets remeasured after initial recognition	194	$ 430
Write-downs of allowance for foreclosed assets after initial recognition	34	20
Noninterest gain (loss) Mortgage banking, net for changes in fair value of LHFS	(1,500)	944
Interest and fees on fair value option LHFS	1,700	$ 1,500
Serviced GNMA loans eligible for repurchase	$ 77,700		$ 78,800

Financing receivable where repayment is expected to be provided substantially through the sale of the collateral.

No definition available.

Name:	trmk_CollateralDependentFinancingReceivable
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Allowance for credit losses on financing receivable where repayment is expected to be provided substantially through the sale of the collateral.

+ References

No definition available.

+ Details

Name:	trmk_CollateralDependentFinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The (re)measured fair value amount, as of the balance sheet date, of all assets obtained in full or partial satisfaction of a debt arrangement through foreclosure proceedings or defeasance; includes real and personal property; equity interests in corporations, partnerships, and joint ventures; and beneficial interests in trusts.

+ References

No definition available.

+ Details

Name:	trmk_ForeclosedAssetsRemeasuredAfterInitialRecognitionFairValue
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest and fees on fair value option LHFS.

+ References

No definition available.

+ Details

Name:	trmk_InterestAndFeesOnFairValueOptionLhfs
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Loans available for repurchase.

+ References

No definition available.

+ Details

Name:	trmk_LoansAvailableForRepurchase
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The overvalued amount that is written down to reduce the carrying value of an asset, that was valued at initial recognition of foreclosure, to the fair value.

+ References

No definition available.

+ Details

Name:	trmk_WriteDownOfAllowanceAfterInitialRecognitionOfForeclosure
Namespace Prefix:	trmk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_FairValueDisclosuresAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482907/825-10-50-30

+ Details

Name:	us-gaap_FairValueOptionChangesInFairValueGainLoss1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration