Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands		12 Months Ended
	Aug. 18, 2006 USD ($) Quarter	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Variable Interest Entity [Line Items]
Face amount of debt issued		$ 50,000
Maturity date		Dec. 15, 2016
Junior subordinated debt securities		$ 61,856	$ 61,856
Total assets		13,352,333	12,678,896
Total liabilities and shareholders' equity		13,352,333	12,678,896
Common securities		14,091	14,076
Net income		$ 108,411	116,038	$ 123,562
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
Basis spread over LIBOR rate (in hundredths)	1.72%
Junior subordinated debt securities	$ 61,900
Consecutive quarters that Trustmark may defer interest payments | Quarter	20
Total assets		$ 61,900	61,900
Total liabilities and shareholders' equity		61,900	61,900
Common securities		60,000	1,900
Net income		45	38	37
Dividends paid		$ 45	$ 38	$ 37