Loans Held for Investment (LHFI) and Allowance for Loan Losses, excluding Covered Loans Part 5 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	$ 89,518	$ 93,510
Charge-offs	(5,376)	(11,132)
Recoveries	3,444	3,483
Net charge-offs	(1,932)	(7,649)
Provisions For Loan Losses	3,293	7,537
Allowance For Loan Losses	90,879	93,398
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	14,888	11,119
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	75,991	82,279
Allowance For Loan Losses	90,879	93,398
Number of Loan Types For Commercial Portfolio	13
Number of Risk Rate Factors For Commercial Loans	360
Number of Unique Qualitative Factors Used To Analyze Commercial Loans	8
The Minimum Score For Qualitative Risk Factor	0
The Maximum Score For Qualitative Risk Factor	100
Real Estate Secured Financing Receivable [Member] \| Construction Land Development And Other Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	27,220	35,562
Charge-offs	(1,526)	(3,494)
Recoveries	0	0
Provisions For Loan Losses	21	4,436
Allowance For Loan Losses	25,715	36,504
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	5,963	6,242
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	19,752	30,262
Allowance For Loan Losses	25,715	36,504
Real Estate Secured Financing Receivable [Member] \| Residential Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	12,650	13,051
Charge-offs	(716)	(2,348)
Recoveries	208	173
Provisions For Loan Losses	598	1,117
Allowance For Loan Losses	12,740	11,993
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	1,240	680
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	11,500	11,313
Allowance For Loan Losses	12,740	11,993
Real Estate Secured Financing Receivable [Member] \| Nonresidential Properties Financing Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	24,358	20,980
Charge-offs	(127)	(1,530)
Recoveries	0	0
Provisions For Loan Losses	3,653	1,760
Allowance For Loan Losses	27,884	21,210
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	5,443	1,415
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	22,441	19,795
Allowance For Loan Losses	27,884	21,210
Real Estate Secured Financing Receivable [Member] \| Other Real Estate Secured Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	3,079	1,582
Charge-offs	(234)	(204)
Recoveries	0	0
Provisions For Loan Losses	176	92
Allowance For Loan Losses	3,021	1,470
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	1,002	41
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	2,019	1,429
Allowance For Loan Losses	3,021	1,470
Commercial And Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	15,868	14,775
Charge-offs	(331)	(827)
Recoveries	821	643
Provisions For Loan Losses	(320)	500
Allowance For Loan Losses	16,038	15,091
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	1,168	2,670
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	14,870	12,421
Allowance For Loan Losses	16,038	15,091
Consumer Loans Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	3,656	5,400
Charge-offs	(1,038)	(1,722)
Recoveries	1,352	1,660
Provisions For Loan Losses	(766)	(504)
Allowance For Loan Losses	3,204	4,834
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	7	18
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	3,197	4,816
Allowance For Loan Losses	3,204	4,834
Other Loans Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance For Loan Losses	2,687	2,160
Charge-offs	(1,404)	(1,007)
Recoveries	1,063	1,007
Provisions For Loan Losses	(69)	136
Allowance For Loan Losses	2,277	2,296
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
Allowance For Loan Losses Disaggregated By Impairment Method, Individually	65	53
Allowance For Loan Losses Disaggregated By Impairment Method, Collectively	2,212	2,243
Allowance For Loan Losses	$ 2,277	$ 2,296

The number of unique loan types the commercial portfolio was delineated into for analysis of loan loss allowance.

No definition available.

Name:	trmk_NumberOfLoanTypesForCommercialPortfolio
Namespace Prefix:	trmk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of risk rate factors utilized for the commercial portfolio.

+ References

No definition available.

+ Details

Name:	trmk_NumberOfRiskRateTypesForCommercialPortfolio
Namespace Prefix:	trmk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of unique qualitative factors used to evaluate the commercial loan portfolio for loan loss allowance.

+ References

No definition available.

+ Details

Name:	trmk_NumberOfUniqueQualitativeFactorsUsedToAnalyzeCommercialLoans
Namespace Prefix:	trmk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The provision for loan losses on loans held-for-sale.

+ References

No definition available.

+ Details

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

- Definition

When presenting a range of scores, the highest potential score under the assessment procedure.

+ References

No definition available.

+ Details

Name:	trmk_QualitativeRiskFactorScoreRangeMaximum
Namespace Prefix:	trmk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

When presenting a range of scores, the lowest potential score under the assessment procedure.

+ References

No definition available.

+ Details

Name:	trmk_QualitativeRiskFactorScoreRangeMinimum
Namespace Prefix:	trmk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the amount charged against earnings during the period as bad debt expense, net of recoveries of previously expensed credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph d

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5212-111524

+ Details

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

- Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953423-111524

-Subparagraph (g)

+ Details

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

- Definition

The valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

+ References

+ Details

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

- Definition

Reduction to the allowance for credit losses related to collections on financing receivables which have been partially or fully charged off as bad debts.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesRecoveries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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

- Definition

Reduction to the allowance for credit losses related to financing receivables deemed uncollectible.

+ References

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The allowance for loan and lease losses represents the reserve to cover probable credit losses related to specifically identified loans and leases, as well as probable credit losses inherent in the remainder of the loan portfolio as of the balance sheet date. For banks, include currently required allocated transfer risk reserves. Include carryover of or adjustments to the allowance for loan losses in connection with business combinations determined to be appropriate.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph d

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 8, 9

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

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

+ Details

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