Borrowings - Junior Subordinated Debt Securities - Additional information (Details) $ in Thousands		12 Months Ended
	Aug. 18, 2006 USD ($) Quarter	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
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		12,678,896	12,250,633
Total liabilities and shareholders' equity		12,678,896	12,250,633
Common securities		14,076	14,060
Net income		$ 116,038	123,562	$ 117,060
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		1,900	1,900
Net income		38	37	38
Dividends paid		$ 38	$ 37	$ 38