Revenue from Contracts with Customers - Summary of Noninterest Income Disaggregated by Reportable Operating Segment and Revenue Stream (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2021	Mar. 31, 2020
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 7,356	$ 10,032
Bank card and other fees		9,472	5,355
Mortgage banking, net		20,804	27,483
Insurance commissions		12,445	11,550
Wealth management		8,416	8,537
Other, net		2,090	2,307
Total Noninterest Income		60,583	65,264
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,356	10,032
Bank card and other fees		7,192	6,732
Insurance commissions		12,445	11,550
Wealth management		8,416	8,537
Other, net		1,443	1,812
Total Noninterest Income		36,852	38,663
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[1]	2,280	(1,377)
Mortgage banking, net	[1]	20,804	27,483
Other, net	[1]	647	495
Total Noninterest Income	[1]	23,731	26,601
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,338	10,012
Bank card and other fees		9,464	5,349
Mortgage banking, net		20,804	27,483
Wealth management		18	86
Other, net		2,028	2,246
Total Noninterest Income		39,652	45,176
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,338	10,012
Bank card and other fees		7,184	6,726
Wealth management		18	86
Other, net		1,388	1,764
Total Noninterest Income		15,928	18,588
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[1]	2,280	(1,377)
Mortgage banking, net	[1]	20,804	27,483
Other, net	[1]	640	482
Total Noninterest Income	[1]	23,724	26,588
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		18	20
Bank card and other fees		8	6
Wealth management		8,398	8,451
Other, net		39	39
Total Noninterest Income		8,463	8,516
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		18	20
Bank card and other fees		8	6
Wealth management		8,398	8,451
Other, net		32	26
Total Noninterest Income		8,456	8,503
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net	[1]	7	13
Total Noninterest Income	[1]	7	13
Insurance Segment [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		12,445	11,550
Other, net		23	22
Total Noninterest Income		12,468	11,572
Insurance Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		12,445	11,550
Other, net		23	22
Total Noninterest Income		$ 12,468	$ 11,572

[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.