| Document and Entity Information | Jan. 26, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jan. 26, 2021 |
| Entity Registrant Name | TRUSTMARK CORP |
| Entity Central Index Key | 0000036146 |
| Entity Emerging Growth Company | false |
| Entity File Number | 000-03683 |
| Entity Incorporation, State or Country Code | MS |
| Entity Tax Identification Number | 64-0471500 |
| Entity Address, Address Line One | 248 East Capitol Street |
| Entity Address, City or Town | Jackson |
| Entity Address, State or Province | MS |
| Entity Address, Postal Zip Code | 39201 |
| City Area Code | 601 |
| Local Phone Number | 208-5111 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of each class | Common Stock, no par value |
| Trading Symbol | TRMK |
| Name of each exchange on which registered | NASDAQ |
