Revenue from Contracts with Customers - Summary of Noninterest Income Disaggregated by Reportable Operating Segment and Revenue Stream (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2022		Sep. 30, 2021		Sep. 30, 2022		Sep. 30, 2021
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 11,318		$ 8,911		$ 30,995		$ 23,880
Bank card and other fees		9,305		8,549		27,914		26,322
Mortgage banking, net		6,876		14,004		24,898		52,141
Insurance commissions		13,911		12,133		41,702		36,795
Wealth management		8,778		9,071		26,934		26,433
Other, net		2,418		1,481		7,531		5,572
Total Noninterest Income		52,606		54,149		159,974		171,143
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,318		8,911		30,995		23,880
Bank card and other fees		7,657		7,570		23,761		23,291
Insurance commissions		13,911		12,133		41,702		36,795
Wealth management		8,778		9,071		26,934		26,433
Other, net		2,169		1,885		6,606		5,069
Total Noninterest Income		43,833		39,570		129,998		115,468
Not Topic 606 [Member
Revenue From Contract With Customer [Line Items]
Bank card and other fees		1,648	[1]	979	[1]	4,153	[2]	3,031	[2]
Mortgage banking, net		6,876	[1]	14,004	[1]	24,898	[2]	52,141	[2]
Other, net		249	[1]	(404)	[1]	925	[2]	503	[2]
Total Noninterest Income		8,773	[1]	14,579	[1]	29,976	[2]	55,675	[2]
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,296		8,893		30,932		23,822
Bank card and other fees		9,292		8,540		27,879		26,295
Mortgage banking, net		6,876		14,004		24,898		52,141
Wealth management		263		13		468		33
Other, net		1,963		1,413		6,993		5,391
Total Noninterest Income		29,690		32,863		91,170		107,682
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		11,296		8,893		30,932		23,822
Bank card and other fees		7,644		7,561		23,726		23,264
Wealth management		263		13		468		33
Other, net		1,724		1,826		6,097		4,913
Total Noninterest Income		20,927		18,293		61,223		52,032
General Banking Segment [Member] | Not Topic 606 [Member
Revenue From Contract With Customer [Line Items]
Bank card and other fees		1,648	[1]	979	[1]	4,153	[2]	3,031	[2]
Mortgage banking, net		6,876	[1]	14,004	[1]	24,898	[2]	52,141	[2]
Other, net		239	[1]	(413)	[1]	896	[2]	478	[2]
Total Noninterest Income		8,763	[1]	14,570	[1]	29,947	[2]	55,650	[2]
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22		18		63		58
Bank card and other fees		13		9		35		27
Wealth management		8,515		9,058		26,466		26,400
Other, net		457		41		541		124
Total Noninterest Income		9,007		9,126		27,105		26,609
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22		18		63		58
Bank card and other fees		13		9		35		27
Wealth management		8,515		9,058		26,466		26,400
Other, net		447		32		512		99
Total Noninterest Income		8,997		9,117		27,076		26,584
Wealth Management Segment [Member] | Not Topic 606 [Member
Revenue From Contract With Customer [Line Items]
Other, net		10	[1]	9	[1]	29	[2]	25	[2]
Total Noninterest Income		10	[1]	9	[1]	29	[2]	25	[2]
Insurance Segment [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		13,911		12,133		41,702		36,795
Other, net		(2)		27		(3)		57
Total Noninterest Income		13,909		12,160		41,699		36,852
Insurance Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		13,911		12,133		41,702		36,795
Other, net		(2)		27		(3)		57
Total Noninterest Income		13,909		12,160		41,699		36,852
Insurance Segment [Member] | Not Topic 606 [Member
Revenue From Contract With Customer [Line Items]
Other, net	[1]	$ 0		$ 0
Total Noninterest Income	[2]					$ 0		$ 0

[1] Noninterest income 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, accretion of the FDIC indemnification asset, 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 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, accretion of the FDIC indemnification asset, 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.