Parent Company Only Financial Information - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements Captions [Line Items]
Income taxes paid	$ 12,435	$ 7,371	$ 24,836
Trustmark Corp (Parent Company Only) [Member]
Condensed Financial Statements Captions [Line Items]
Income taxes paid	12,400	7,400	24,800
Interest paid		$ 283	$ 600
Interest received	$ 320