Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands		12 Months Ended
	Aug. 18, 2006 USD ($) qtr	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Variable Interest Entity [Line Items]
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		18,722,189	18,015,478	$ 17,595,636
Total liabilities and shareholders' equity		18,722,189	18,015,478
Common securities		12,725	12,705
Net income		165,489	71,887	147,365
Trustmark Preferred Capital Trust I [Member] | Junior Subordinated Debt Securities [Member]
Variable Interest Entity [Line Items]
Face amount of debt issued	$ 60,000
Maturity date	Sep. 30, 2036
Variable interest rate, description	three-month Chicago Mercantile Exchange, Inc. (CME) SOFR
Basis spread over SOFR rate (in hundredths)	0.26%
Debt instrument interest rate margin	1.72%
Junior subordinated debt securities	$ 61,900
Consecutive quarters that Trustmark may defer interest payments | qtr	20
Total assets		61,900	61,900
Total liabilities and shareholders' equity		61,900	61,900
Trust preferred securities		60,000		60,000
Common securities		1,900	1,900
Net income		132	66	36
Dividends paid		$ 132	$ 66	$ 36