Defined Benefit and Other Postretirement Benefits - Estimated Future Benefit Payments and Other Disclosures (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Supplemental Retirement Plan [Member]
Estimated future benefit payments [Abstract]
2020	$ 3,963
2021	4,051
2022	4,284
2023	4,124
2024	4,144
2025 - 2029	17,840
Trustmark Corporation Pension Plan for Certain Employees of Acquired Financial Institutions [Member] \| Trustmark Capital Accumulation Plan [Member]
Estimated future benefit payments [Abstract]
2020	1,147
2021	1,056
2022	873
2023	1,220
2024	997
2025 - 2029	$ 2,443

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fifth fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in fourth fiscal year following latest fiscal year.

+ References

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Amount of benefits for defined benefit plan expected to be paid in third fiscal year following latest fiscal year.

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Amount of benefits for defined benefit plan expected to be paid in second fiscal year following latest fiscal year.

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