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, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		$ 7,613	$ 6,397	$ 14,969	$ 16,429
Bank card and other fees		8,301	7,717	17,773	13,072
Mortgage banking, net		17,333	33,745	38,137	61,228
Insurance commissions		12,217	11,868	24,662	23,418
Wealth management		8,946	7,571	17,362	16,108
Other, net		2,001	2,213	4,091	4,520
Total Noninterest Income		56,411	69,511	116,994	134,775
Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,613	6,397	14,969	16,429
Bank card and other fees		8,529	6,557	15,721	13,289
Insurance commissions		12,217	11,868	24,662	23,418
Wealth management		8,946	7,571	17,362	16,108
Other, net		1,741	1,420	3,184	3,232
Total Noninterest Income		39,046	33,813	75,898	72,476
Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[1]	(228)	1,160	2,052	(217)
Mortgage banking, net	[1]	17,333	33,745	38,137	61,228
Other, net	[1]	260	793	907	1,288
Total Noninterest Income	[1]	17,365	35,698	41,096	62,299
General Banking Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,591	6,380	14,929	16,392
Bank card and other fees		8,291	7,709	17,755	13,058
Mortgage banking, net		17,333	33,745	38,137	61,228
Wealth management		2	79	20	165
Other, net		1,950	2,138	3,978	4,384
Total Noninterest Income		35,167	50,051	74,819	95,227
General Banking Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		7,591	6,380	14,929	16,392
Bank card and other fees		8,519	6,549	15,703	13,275
Wealth management		2	79	20	165
Other, net		1,699	1,354	3,087	3,118
Total Noninterest Income		17,811	14,362	33,739	32,950
General Banking Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Bank card and other fees	[1]	(228)	1,160	2,052	(217)
Mortgage banking, net	[1]	17,333	33,745	38,137	61,228
Other, net	[1]	251	784	891	1,266
Total Noninterest Income	[1]	17,356	35,689	41,080	62,277
Wealth Management Segment [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22	17	40	37
Bank card and other fees		10	8	18	14
Wealth management		8,944	7,492	17,342	15,943
Other, net		44	33	83	72
Total Noninterest Income		9,020	7,550	17,483	16,066
Wealth Management Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Service charges on deposit accounts		22	17	40	37
Bank card and other fees		10	8	18	14
Wealth management		8,944	7,492	17,342	15,943
Other, net		35	24	67	50
Total Noninterest Income		9,011	7,541	17,467	16,044
Wealth Management Segment [Member] | Not Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Other, net	[1]	9	9	16	22
Total Noninterest Income	[1]	9	9	16	22
Insurance Segment [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		12,217	11,868	24,662	23,418
Other, net		7	42	30	64
Total Noninterest Income		12,224	11,910	24,692	23,482
Insurance Segment [Member] | Topic 606 [Member]
Revenue From Contract With Customer [Line Items]
Insurance commissions		12,217	11,868	24,662	23,418
Other, net		7	42	30	64
Total Noninterest Income		$ 12,224	$ 11,910	$ 24,692	$ 23,482

[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.