Parent Company Only Financial Information - Parent Only Financial Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Assets
Other assets	$ 677,230	$ 752,568
Total Assets	18,152,422	18,722,189
Liabilities and Shareholders' Equity:
Subordinated notes	123,702	123,482
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,962,327	1,661,847	$ 1,492,268	$ 1,741,311
Total Liabilities and Shareholders' Equity	18,152,422	18,722,189
Expense:
Net Income	223,009	165,489	71,887
Operating Activities
Net income	223,009	165,489	71,887
Adjustments to reconcile net income to net cash provided by operating activities:
Other	(32,549)	1,192	(57,359)
Net cash from operating activities	116,929	196,887	296,516
Financing Activities
Common stock dividends	(56,790)	(56,653)	(56,679)
Repurchase and retirement of common stock	(7,499)	0	(24,604)
Net cash from financing activities	(809,615)	455,043	451,844
Net change in cash and cash equivalents	(408,092)	240,756	(1,532,042)
Trustmark Corp (Parent Company Only) [Member]
Assets
Investment in banks	2,062,555	1,770,392
Other assets	86,907	77,901
Total Assets	2,149,462	1,848,293
Liabilities and Shareholders' Equity:
Accrued expense	1,577	1,108
Subordinated notes	123,702	123,482
Junior subordinated debt securities	61,856	61,856
Shareholders' equity	1,962,327	1,661,847
Total Liabilities and Shareholders' Equity	2,149,462	1,848,293
Revenue:
Dividends received from banks	82,536	67,189	89,733
Earnings of subsidiaries over distributions	148,884	106,388	(11,269)
Other income	165	163	94
Total Revenue	231,585	173,740	78,558
Expense:
Other expense	8,576	8,251	6,671
Total Expense	8,576	8,251	6,671
Net Income	223,009	165,489	71,887
Operating Activities
Net income	223,009	165,489	71,887
Adjustments to reconcile net income to net cash provided by operating activities:
Net change in investment in subsidiaries	(148,884)	(106,388)	11,269
Other	(835)	(797)	(1,550)
Net cash from operating activities	73,290	58,304	81,606
Financing Activities
Common stock dividends	(56,790)	(56,653)	(56,679)
Repurchase and retirement of common stock	(7,499)	0	(24,604)
Net cash from financing activities	(64,289)	(56,653)	(81,283)
Net change in cash and cash equivalents	9,001	1,651	323
Cash and cash equivalents at beginning of year	77,511	75,860	75,537
Cash and cash equivalents at end of year	$ 86,512	$ 77,511	$ 75,860