Parent Company Only Financial Information - Parent Only Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Assets
Other assets	$ 770,838	$ 568,177
Total Assets	18,015,478	17,595,636	$ 16,551,840
Liabilities and Shareholders' Equity:
Subordinated notes	123,262	123,042
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,492,268	1,741,311	1,741,117	$ 1,660,702
Total Liabilities and Shareholders' Equity	18,015,478	17,595,636
Expense:
Net Income	71,887	147,365	160,025
Operating Activities
Net income	71,887	147,365	160,025
Adjustments to reconcile net income to net cash provided by operating activities:
Other	(57,359)	(9,601)	27,699
Net cash from operating activities	296,516	348,771	65,346
Financing Activities
Proceeds from subordinated notes	0	0	122,900
Common stock dividends	(56,679)	(58,085)	(58,769)
Repurchase and retirement of common stock	(24,604)	(61,799)	(27,538)
Net cash from financing activities	451,844	970,568	2,745,957
Net change in cash and cash equivalents	(1,532,042)	314,325	1,593,588
Trustmark Corp (Parent Company Only) [Member]
Assets
Investment in banks	1,602,169	1,851,398
Other assets	76,325	75,995
Total Assets	1,678,494	1,927,393
Liabilities and Shareholders' Equity:
Accrued expense	1,108	1,184
Subordinated notes	123,262	123,042
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,492,268	1,741,311
Total Liabilities and Shareholders' Equity	1,678,494	1,927,393
Revenue:
Dividends received from banks	89,733	45,284	109,243
Earnings of subsidiaries over distributions	11,269	108,141	53,724
Other income	94	95	66
Total Revenue	78,558	153,520	163,033
Expense:
Other expense	6,671	6,155	3,008
Total Expense	6,671	6,155	3,008
Net Income	71,887	147,365	160,025
Operating Activities
Net income	71,887	147,365	160,025
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in investment in subsidiaries	11,269	(108,141)	(53,724)
Other	(1,550)	(2,078)	(326)
Net cash from operating activities	81,606	37,146	105,975
Financing Activities
Proceeds from subordinated notes			122,900
Common stock dividends	(56,679)	(58,085)	(58,769)
Repurchase and retirement of common stock	(24,604)	(61,799)	(27,538)
Net cash from financing activities	(81,283)	(119,884)	36,593
Net change in cash and cash equivalents	323	(82,738)	142,568
Cash and cash equivalents at beginning of year	75,537	158,275	15,707
Cash and cash equivalents at end of year	$ 75,860	$ 75,537	$ 158,275