Covered Loans, Covered Other Real Estate and FDIC Indemnification Asset (Details) (USD $)	9 Months Ended
Sep. 30, 2011	Apr. 15, 2011
Covered Loans, Covered Other Real Estate and FDIC Indemnification Asset [Abstract]
Assets acquired not subject to loss share agreements with the FDIC		$ 9,600,000
Covered loans acquired and activity [Abstract]
Contractually required principal and interest		145,864,000
Nonaccretable difference		(38,345,000)
Cash flows expected to be collected		107,519,000
Accretable yield		(13,579,000)
Other revolving loans		3,830,000
Fair value at acquisition date		97,770,000
Loans secured by real estate: [Abstract]
Covered loans acquired		97,770,000
Accretion	2,441,000
Payments received	(21,147,000)
Covered loans	79,064,000
Covered Other Real Estate [Abstract]
Covered other real estate	7,500,000
Change in accretable difference on covered loans [Abstract]
Accretable yield acquired		(13,579,000)
Accretion	2,441,000
Other activity, net	0
Carrying value, end of period	(11,138,000)
FDIC Indemnification Asset [Abstract]
FDIC indemnification asset	0	33,333,000
Accretion income	103,000
Other activity, net	0
FDIC indemnification asset	33,436,000	33,333,000
Acquired revolving credit agreements		3,900,000
Real Estate Secured Financing Receivable [Member]
Covered Other Real Estate [Abstract]
Covered other real estate	7,197,000
Real Estate Secured Financing Receivable [Member] \| Construction Land Development And Other Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	4,024,000
Covered Other Real Estate [Abstract]
Covered other real estate	1,624,000
Real Estate Secured Financing Receivable [Member] \| Residential 1-4 Family Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	32,735,000
Covered Other Real Estate [Abstract]
Covered other real estate	934,000
Real Estate Secured Financing Receivable [Member] \| Nonresidential Nonfarm Properties Financing Receivables [Member]
Loans secured by real estate: [Abstract]
Covered loans	33,601,000
Covered Other Real Estate [Abstract]
Covered other real estate	4,523,000
Real Estate Secured Financing Receivable [Member] \| Other Real Estate Secured Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	5,294,000
Covered Other Real Estate [Abstract]
Covered other real estate	116,000
Other Loans Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	1,480,000
Commercial And Industrial Loans Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	1,772,000
Consumer Loans Financing Receivable [Member]
Loans secured by real estate: [Abstract]
Covered loans	$ 158,000

Carrying amount as of the balance sheet date of accretable difference on covered loans acquired.

Name:	trmk_CarryingValueAccretableDifference
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the aggregate carrying amount of loans covered by loss sharing agreement with Federal Deposit Insurance Corporation that partially indemnifies bank against losses.

+ Details

Name:	trmk_CarryingValueCoveredLoans
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	trmk_ChangeInAccretableDifferenceOnCoveredLoansAbstract
Namespace Prefix:	trmk
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net payments received during the period on purchased loans. Monetary Duration Credit

+ Details

Name:	trmk_ChangeInCarryingAmountOfLoansPaymentsReceivedNet
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	trmk_CoveredLoansCoveredOtherRealEstateAndFdicIndemnificationAssetAbstract
Namespace Prefix:	trmk
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	trmk_CoveredOtherRealEstateAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of receivable assets originating from the indemnification agreement with FDIC to partially cover losses on certain loans and other real estate.

+ Details

Name:	trmk_FdicIndemnificationAsset
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	trmk_FdicIndemnificationAssetAbstract
Namespace Prefix:	trmk
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase (decrease) in other receivables related to accretion of indemnification assets.

+ Details

Name:	trmk_Increasedecreaseinotherreceivablesaccretionindemnificationassets
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the change in the carrying value of Indemnification asset (receivable from FDIC) for covered acquired impaired loans and other real estate.

+ Details

Name:	trmk_IndemnificationAssetOtherActivityNet
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represent's the purchase price allocation to Heritage assets acquired that are not subject to loss share agreements with the FDIC.

+ Details

Name:	trmk_LoansAcquiredNotSubjectToLossShareAgreements
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	trmk_LoansSecuredByRealEstateAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For receivables acquired this element represents the fair value of the receivables acquired, by major class of receivable, such as loans, direct finance leases (as defined), and any other class of receivables.

+ Details

Name:	trmk_RevolvingCreditFacilityPurchasedFairValueDisclosure
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Revolving credit loans receivables acquired at fair value of the receivables acquired.

+ Details

Name:	trmk_RevolvingCreditLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtA
Namespace Prefix:	trmk
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount as of the balance sheet date of other real estate.

+ Details

Name:	trmk_TotalCoveredOtherRealEstate
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of the loan's contractually required payments receivable in excess of the amount of its cash flows expected to be collected. This relates to loans with deteriorating 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.

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNonaccretableDifference
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans not accounted for as 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 AICPA

-Name Statement of Position (SOP)

-Number 03-3

-Paragraph 16

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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=6891207&loc=d3e13503-111538

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYield
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The increases in the aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan. This relates to loans not accounted for as 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, due to the acquisition of similar loans not accounted for as debt securities during the period.

+ References

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAccretableYieldAdditions
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. This relates to loans not accounted for as 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 AICPA

-Name Statement of Position (SOP)

-Number 03-3

-Paragraph 16

-Subparagraph a(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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=6891207&loc=d3e13503-111538

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

Name:	us-gaap_CertainLoansAcquiredInTransferNotAccountedForAsDebtSecuritiesAcquiredDuringPeriodAtAcquisitionAtFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The investor's estimate, at acquisition, of the amount and timing of undiscounted principal, interest, and other cash flows expected to be collected. This would be the investor's best estimate of cash flows, including the effect of prepayments if considered, that is used in determining the acquisition price, and, in a business combination, the investor's estimate of fair value for purposes of acquisition price allocation. This relates to loans not accounted for as 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

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

The total undiscounted amount of all uncollected contractual principal and contractual interest payments both past due and scheduled for the future, adjusted for the timing of prepayments, if considered, less any reduction by the investor at the acquisition date. This relates to loans not accounted for as 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

+ Details

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Data Type:	xbrli:monetaryItemType
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