Time period when debt instrument is scheduled to be fully repaid.

No definition available.

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- Definition

Represents the number of outstanding long-term FHLB advances.

+ References

No definition available.

+ Details

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- Definition

Weighted average cost related to FHLB advances.

+ References

No definition available.

+ Details

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Namespace Prefix:	trmk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

+ Details

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

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Interest expense incurred during the reporting period on long-term borrowings associated with Federal Home Loan Bank and Federal Reserve Bank advances.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of addition (reduction) to the amount at which a liability could be incurred (settled) in a current transaction between willing parties.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Article 5
-Subsection 19, 20, 22

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 10
-Section F

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_FinancialInstrumentAxis=trmk_LongTermBorrowingMember
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- Details

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Borrowings - Long-term Debt Instruments - Additional information (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) Loan	Dec. 31, 2014 USD ($) Loan	Dec. 31, 2013 USD ($)
Long-Term Borrowings [Abstract]
Maturity date	Dec. 15, 2016
Interest rate (in hundredths)	5.673%
Face amount of debt issued	$ 50,000
Subordinated notes	$ 49,969	$ 49,936
Maximum [Member]
Long-Term Borrowings [Abstract]
Maturity period	1 year
Federal Home Loan Bank Advances [Member] \| Dallas [Member]
Long-Term Borrowings [Abstract]
Number of outstanding long-term FHLB advances \| Loan	1
Weighted average remaining maturity	1 year 11 months 19 days
Weighted-average cost related to FHLB advances (in hundredths)	0.32%
Maturity date	Dec. 27, 2017
Federal Home Loan Bank Advances [Member] \| Atlanta [Member]
Long-Term Borrowings [Abstract]
Number of outstanding long-term FHLB advances \| Loan	4	4
Weighted average remaining maturity	6 years 2 months 16 days	7 years 1 month 17 days
Weighted-average cost related to FHLB advances (in hundredths)	1.00%	1.11%
Interest expense, long-term	$ 49	$ 45	$ 57
Federal Home Loan Bank Advances [Member] \| Atlanta [Member] \| Minimum [Member]
Long-Term Borrowings [Abstract]
Interest rate (in hundredths)	0.08%	0.08%
Federal Home Loan Bank Advances [Member] \| Atlanta [Member] \| Maximum [Member]
Long-Term Borrowings [Abstract]
Interest rate (in hundredths)	6.50%	6.50%
BancTrust [Member] \| Long Term Borrowing [Member] \| Federal Home Loan Bank Advances [Member] \| Fair Market Value Adjustment [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	$ 3	$ 7
BancTrust [Member] \| Long Term Borrowing [Member] \| Federal Home Loan Bank Advances [Member] \| Dallas [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	500,000
BancTrust [Member] \| Long Term Borrowing [Member] \| Federal Home Loan Bank Advances [Member] \| Atlanta [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	1,200	1,200
BancTrust [Member] \| Long Term Borrowing [Member] \| Federal Home Loan Bank Advances [Member] \| Atlanta [Member] \| Minimum [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	15	23
BancTrust [Member] \| Long Term Borrowing [Member] \| Federal Home Loan Bank Advances [Member] \| Atlanta [Member] \| Maximum [Member]
Long-Term Borrowings [Abstract]
Long-term FHLB advances	$ 868	$ 913