Revenue from Contracts with Customers - Summary of Noninterest Income Disaggregated by Reportable Operating Segment and Revenue Stream (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024		Jun. 30, 2023		Jun. 30, 2024		Jun. 30, 2023
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	$ 10,924		$ 10,695		$ 21,882		$ 21,031
Bank card and other fees	9,225		8,917		16,653		16,720
Mortgage banking, net	4,204		6,600		13,119		14,239
Wealth management	9,692		8,882		18,644		17,662
Other, net	7,461		2,735		10,563		5,255
Security gains (losses), net	(182,792)				(182,792)
Total Noninterest Income (Loss)	(141,286)		37,829		(101,931)		74,907
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	10,924		10,695		21,882		21,031
Bank card and other fees	8,467		8,049		15,695		15,703
Wealth management	9,692		8,882		18,644		17,662
Other, net	7,289		2,968		10,679		6,001
Total Noninterest Income (Loss)	36,372		30,594		66,900		60,397
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	758	[1]	868	[1]	958	[2]	1,017	[2]
Mortgage banking, net	4,204	[1]	6,600	[1]	13,119	[2]	14,239	[2]
Other, net	172	[1]	(233)	[1]	(116)	[2]	(746)	[2]
Security gains (losses), net	(182,792)	[1]			(182,792)	[2]
Total Noninterest Income (Loss)	(177,658)	[1]	7,235	[1]	(168,831)	[2]	14,510	[2]
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	10,903		10,673		21,839		20,988
Bank card and other fees	9,186		8,904		16,578		16,696
Mortgage banking, net	4,204		6,600		13,119		14,239
Wealth management	174		215		363		448
Other, net	7,329		2,603		10,295		4,983
Security gains (losses), net	(182,792)				(182,792)
Total Noninterest Income (Loss)	(150,996)		28,995		(120,598)		57,354
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	10,903		10,673		21,839		20,988
Bank card and other fees	8,428		8,036		15,620		15,679
Wealth management	174		215		363		448
Other, net	7,251		2,932		10,599		5,920
Total Noninterest Income (Loss)	26,756		21,856		48,421		43,035
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	758	[1]	868	[1]	958	[2]	1,017	[2]
Mortgage banking, net	4,204	[1]	6,600	[1]	13,119	[2]	14,239	[2]
Other, net	78	[1]	(329)	[1]	(304)	[2]	(937)	[2]
Security gains (losses), net	(182,792)	[1]			(182,792)	[2]
Total Noninterest Income (Loss)	(177,752)	[1]	7,139	[1]	(169,019)	[2]	14,319	[2]
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	21		22		43		43
Bank card and other fees	39		13		75		24
Wealth management	9,518		8,667		18,281		17,214
Other, net	132		132		268		272
Total Noninterest Income (Loss)	9,710		8,834		18,667		17,553
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts	21		22		43		43
Bank card and other fees	39		13		75		24
Wealth management	9,518		8,667		18,281		17,214
Other, net	38		36		80		81
Total Noninterest Income (Loss)	9,616		8,738		18,479		17,362
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net	94	[1]	96	[1]	188	[2]	191	[2]
Total Noninterest Income (Loss)	$ 94	[1]	$ 96	[1]	$ 188	[2]	$ 191	[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.