The amount of net gain (loss) recognized as noninterest income in bank card and other fees on derivative instruments not designated as hedging instruments.

No definition available.

+ Details

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

- Definition

The amount of net gain (loss) recognized as noninterest income in mortgage banking, net on derivative instruments not designated as hedging instruments.

+ References

No definition available.

+ Details

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

- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=trmk_AccumulatedOtherComprehensiveIncomeLossAndOtherInterestExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=trmk_MortgageBankingNetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=trmk_BankcardAndOtherFeesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Financial Instruments - Effects of Derivative Instruments on Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivatives in Hedging Relationships [Member] \| Accumulated Other Comprehensive Income (Loss) and Other Interest Expense [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) reclassified from accumulated other comprehensive income (loss) and recognized in other interest expense		$ 141		$ 312
Derivatives not Designated as Hedging Instruments [Member] \| Mortgage Banking, Net [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in mortgage banking, net	$ 12,395	7,944	$ 45,881	12,797
Derivatives not Designated as Hedging Instruments [Member] \| Bank Card and Other Fees [Member]
Derivatives, Fair Value [Line Items]
Amount of gain (loss) recognized in bank card and other fees	$ (76)	$ (487)	$ (1,736)	$ (743)