The carrying value of acquired loans during the period.

No definition available.

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

- Definition

Reserve for loans impairments recorded after acquisition as a result of current information and events which result in it being probable that estimated cash flows will be less than previously expected or because actual cash flows are less than cash flows previously expected. This relates to loans not accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

+ Details

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

- Definition

The recorded balance, net of any applicable reductions (for example, unamortized accretable yield and allowance for loan losses). This relates to loans not accounted for debt securities with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 15
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=trmk_NoncoveredLoansMember
Namespace Prefix:
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- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=trmk_CoveredLoansMember
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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=trmk_ConstructionLandDevelopmentAndOtherFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CollateralAxis=us-gaap_RealEstateMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=trmk_ResidentialFinancingReceivableMember
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Data Type:	na
Balance Type:
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- Details

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- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=trmk_OtherRealEstateSecuredFinancingReceivableMember
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- Details

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Namespace Prefix:
Data Type:	na
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- Details

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Data Type:	na
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- Details

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Acquired Loans - Schedule of Covered and Noncovered Acquired Loans by Type (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 364,755	$ 390,411
Less allowance for loan losses, acquired loans	13,535	11,992	$ 11,837	$ 12,059
Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	349,781	372,711
Less allowance for loan losses, acquired loans	13,212	11,259	11,106	10,541
Net acquired loans	336,569	361,452
Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	14,974	17,700
Less allowance for loan losses, acquired loans	323	733	$ 731	$ 1,518
Net acquired loans	14,651	16,967
Construction, Land Development and Other Land [Member] \| Loans Secured by Real Estate [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	41,097	41,623
Construction, Land Development and Other Land [Member] \| Loans Secured by Real Estate [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	387	1,021
Secured by 1-4 Family Residential Properties [Member] \| Loans Secured by Real Estate [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	81,314	86,950
Secured by 1-4 Family Residential Properties [Member] \| Loans Secured by Real Estate [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	8,564	10,058
Secured by Nonfarm, Nonresidential Properties [Member] \| Loans Secured by Real Estate [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	126,177	135,626
Secured by Nonfarm, Nonresidential Properties [Member] \| Loans Secured by Real Estate [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	3,679	4,638
Other Real Estate Secured [Member] \| Loans Secured by Real Estate [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	24,374	23,860
Other Real Estate Secured [Member] \| Loans Secured by Real Estate [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	1,132	1,286
Commercial and Industrial Loans [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	51,663	55,075
Commercial and Industrial Loans [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	1,143	624
Consumer Loans [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	5,027	5,641
Consumer Loans [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	0	0
Other Loans [Member] \| Noncovered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	20,129	23,936
Other Loans [Member] \| Covered Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Acquired loans	$ 69	$ 73