Name:	trmk_ForeclosedAssetsRemeasuredAfterInitialRecognitionFairValue
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Refers to interest and fees derived on loans held for sale.

No definition available.

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

Loans available for repurchase.

No definition available.

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

Nonfinancial Assets and Liabilities [Abstract]

No definition available.

Name:	trmk_NonfinancialAssetsAndLiabilitiesAbstract
Namespace Prefix:	trmk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

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.

No definition available.

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

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

Name:	us-gaap_FairValueOptionChangesInFairValueGainLoss1
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Data Type:	xbrli:monetaryItemType
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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesIndividuallyEvaluatedForImpairment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The balance of financing receivables that were individually evaluated for impairment.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524