The maximum maturity (in years) of outstanding letters of credit issued by company.

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

- Definition

Number of lawsuits naming entity as a defendant, in number of lawsuits.

+ Details

Name:	trmk_NumberOfLawsuitsNamedAsDefendant
Namespace Prefix:	trmk
Data Type:	xbrli:integerItemType
Balance Type:	na
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.

+ Details

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

- Definition

The estimated maximum amount of possible loss from the contingency.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14557-108349

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 14

-Paragraph 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14435-108349

+ Details

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

- Definition

The carrying amount (fair value) as of the balance sheet date of securities held that had been pledged by counterparties under financing and lending arrangements, pursuant to which the entity has the right by agreement or custom to sell or re-pledge such securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5086-111524

+ Details

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

Contingencies (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011 Trustmark Corporation [Member] Standby Letters of Credit [Member]	Sep. 30, 2010 Trustmark Corporation [Member] Standby Letters of Credit [Member]	Sep. 30, 2011 Trustmark National Bank [Member] Pending or Threatened Litigation [Member]
Loss Contingencies [Line Items]
Maximum potential exposure to credit loss in the event of nonperformance		$ 169.8	$ 186.0
Letters of Credit, Maturity Term - Maximum (in years)	3 Y
Collateral Held, Fair Value	$ 55.3
Lawsuits Naming Entity as Defendant, number				2