Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands		12 Months Ended
	Aug. 18, 2006 USD ($) qtr	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Variable Interest Entity [Line Items]
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		17,595,636	16,551,840	$ 13,497,877
Total liabilities and shareholders' equity		17,595,636	16,551,840
Common securities		12,845	13,215
Net income		147,365	$ 160,025	150,460
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 LIBOR		three-month LIBOR
Basis spread over LIBOR rate (in hundredths)	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		36	51	79
Dividends paid		$ 36	$ 51	$ 79