Loans held for sale eligible for repurchase that are equal to or greater than 90 days past due.

No definition available.

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

- Definition

Credit amount used in baseline evaluation.

+ References

No definition available.

+ Details

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

- Definition

Exposure for commercial non accrual loans to be reviewed on an individual basis.

+ References

No definition available.

+ Details

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

- Definition

Exposure for commercial accrual loans modified to borrowers experiencing financial difficulties deemed to be reviewed on individual basis..

+ References

No definition available.

+ Details

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

- Definition

Financing Receivable [Abstract]

+ References

No definition available.

+ Details

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

- Definition

This line item represents the number of key quality ratios on which entity's loan portfolio credit quality indicators focused.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

The amount of the outstanding principal of a loan may be repurchased under GNMA Optional repurchase Program for loans in a pool that become delinquent.

+ References

No definition available.

+ Details

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Namespace Prefix:	trmk_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum of days past due used as a baseline for the evaluation of collateral documentation under the entity's loan policy.

+ References

No definition available.

+ Details

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Namespace Prefix:	trmk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 29
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-29

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-5

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 79
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479294/326-20-55-79

+ Details

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

- Definition

Amount of credit loss expense (reversal of expense) for financing receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(11))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

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

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

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LHFI and ACL, LHFI - Additional Information (Details 2) $ in Thousands	3 Months Ended
	Mar. 31, 2025 USD ($) KeyRatio	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Financing Receivable Recorded Investment [Line Items]
Number of days used as baseline in evaluating collateral documentation exceptions for loan policy	90 days
Number of key quality ratios \| KeyRatio	6
Exposure for commercial non accrual loans to be reviewed on individual basis	$ 500
LHFS past due 90 days or more	$ 71,700		$ 71,300
Percentage of outstanding principal to be repurchased under GNMA optional repurchase program	100.00%
Exposure for Modified Commercial Accrual Loans Deemed To Be Reviewed On Individual Basis	$ 500
Loans Held for Investment [Member]
Financing Receivable [Abstract]
PCL	8,125	$ 7,708
Minimum [Member]
Financing Receivable [Abstract]
Credit amount used as baseline in evaluating loan policy	$ 100