Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018		Dec. 31, 2018
Segment Reporting Information [Line Items]
Net interest income	$ 104,808	$ 102,093
Provision for loan losses, net	1,689	4,111
Noninterest income	41,491	46,793	[1]
Noninterest expense	106,021	102,465
Income Before Income Taxes	38,589	42,310
Income taxes	5,250	5,480
Net Income	33,339	36,830
Selected Financial Information
Total assets	13,478,017	13,463,439		$ 13,286,460
Depreciation and amortization	9,337	9,376
General Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	103,787	100,707
Provision for loan losses, net	1,691	4,111
Noninterest income	22,913	29,760	[1]
Noninterest expense	90,659	87,990
Income Before Income Taxes	34,350	38,366
Income taxes	4,190	4,486
Net Income	30,160	33,880
Selected Financial Information
Total assets	13,297,961	13,288,601
Depreciation and amortization	9,139	9,210
Wealth Management [Member]
Segment Reporting Information [Line Items]
Net interest income	966	1,331
Provision for loan losses, net	(2)
Noninterest income	7,703	7,614	[1]
Noninterest expense	7,019	6,876
Income Before Income Taxes	1,652	2,069
Income taxes	409	517
Net Income	1,243	1,552
Selected Financial Information
Total assets	108,464	107,503
Depreciation and amortization	69	27
Insurance [Member]
Segment Reporting Information [Line Items]
Net interest income	55	55
Noninterest income	10,875	9,419	[1]
Noninterest expense	8,343	7,599
Income Before Income Taxes	2,587	1,875
Income taxes	651	477
Net Income	1,936	1,398
Selected Financial Information
Total assets	71,592	67,335
Depreciation and amortization	$ 129	$ 139

[1] During the first quarter of 2019, Trustmark revised the composition of its operating segments by moving the Private Banking Group from the General Banking Segment to the Wealth Management Segment as a result of a change in supervision of this group for segment reporting purposes. The prior period amounts presented include reclassifications to conform to the current period presentation.