Name:	trmk_AssumedAveragePrepaymentSpeed
Namespace Prefix:	trmk_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

The period of time the company is required to provide a response to putback requests.

No definition available.

Name:	trmk_PeriodOfPutbackResponse
Namespace Prefix:	trmk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Schedule of changes in the reserve for mortgage loan [Abstract]

No definition available.

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

Servicing fee income percentage of outstanding balance of underlying loans.

No definition available.

Name:	trmk_ServicingFeeIncomePercentageOfOutstandingBalanceOfUnderlyingLoans
Namespace Prefix:	trmk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The noninterest income derived from mortgage banking activities (fees and commissions), excluding fees earned from servicing third-party assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13 (d))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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

The carrying amount of mortgage loans on real estate that were sold during the reporting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04.(c) Schedule IV)
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-29.6)
-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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

- References

No definition available.

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

Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746