Revenue from Contracts with Customers - Summary of Noninterest Income (Loss) Disaggregated by Reportable Operating Segment and Revenue Stream (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2024		Sep. 30, 2023		Sep. 30, 2024		Sep. 30, 2023
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 11,272		$ 11,074		$ 33,154		$ 32,105
Bank card and other fees		7,931		8,217		24,584		24,937
Mortgage banking, net		6,119		6,458		19,238		20,697
Wealth management		9,288		8,773		27,932		26,435
Other, net		2,952		2,399		13,515		7,654
Security gains (losses), net						(182,792)
Total Noninterest Income (Loss)		37,562		36,921		(64,369)		111,828
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,272		11,074		33,154		32,105
Bank card and other fees		7,713		7,344		23,408		23,047
Wealth management		9,288		8,773		27,932		26,435
Other, net		3,195		2,884		13,874		8,885
Total Noninterest Income (Loss)		31,468		30,075		98,368		90,472
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees		218	[1]	873	[1]	1,176	[2]	1,890	[2]
Mortgage banking, net		6,119	[1]	6,458	[1]	19,238	[2]	20,697	[2]
Other, net		(243)	[1]	(485)	[1]	(359)	[2]	(1,231)	[2]
Security gains (losses), net	[2]					(182,792)
Total Noninterest Income (Loss)		6,094	[1]	6,846	[1]	(162,737)	[2]	21,356	[2]
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,250		11,052		33,089		32,040
Bank card and other fees		7,879		8,205		24,457		24,901
Mortgage banking, net		6,119		6,458		19,238		20,697
Wealth management		175		202		538		650
Other, net		2,799		2,264		13,094		7,247
Security gains (losses), net						(182,792)
Total Noninterest Income (Loss)		28,222		28,181		(92,376)		85,535
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,250		11,052		33,089		32,040
Bank card and other fees		7,661		7,332		23,281		23,011
Wealth management		175		202		538		650
Other, net		3,136		2,843		13,735		8,763
Total Noninterest Income (Loss)		22,222		21,429		70,643		64,464
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees		218	[1]	873	[1]	1,176	[2]	1,890	[2]
Mortgage banking, net		6,119	[1]	6,458	[1]	19,238	[2]	20,697	[2]
Other, net		(337)	[1]	(579)	[1]	(641)	[2]	(1,516)	[2]
Security gains (losses), net	[2]					(182,792)
Total Noninterest Income (Loss)		6,000	[1]	6,752	[1]	(163,019)	[2]	21,071	[2]
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22		22		65		65
Bank card and other fees		52		12		127		36
Wealth management		9,113		8,571		27,394		25,785
Other, net		153		135		421		407
Total Noninterest Income (Loss)		9,340		8,740		28,007		26,293
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22		22		65		65
Bank card and other fees		52		12		127		36
Wealth management		9,113		8,571		27,394		25,785
Other, net		59		41		139		122
Total Noninterest Income (Loss)		9,246		8,646		27,725		26,008
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net		94	[1]	94	[1]	282	[2]	285	[2]
Total Noninterest Income (Loss)		$ 94	[1]	$ 94	[1]	$ 282	[2]	$ 285	[2]

[1] Noninterest income (loss) not in scope for FASB ASC Topic 606 includes customer derivatives revenue and miscellaneous credit card fee income within bank card and other fees; mortgage banking, net; amortization of tax credits, cash surrender value on various life insurance policies, earnings on Trustmark’s non-qualified deferred compensation plans, other partnership investments and rental income within other, net; and security gains (losses), net.

[2] Noninterest income (loss) not in scope for FASB ASC Topic 606 includes customer derivatives revenue and miscellaneous credit card fee income within bank card and other fees; mortgage banking, net; amortization of tax credits, cash surrender value on various life insurance policies, earnings on Trustmark’s non-qualified deferred compensation plans, other partnership investments and rental income within other, net; and security gains (losses), net.