LHFI and ACL, LHFI - Change in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		$ 117,306
PCL, LHFI	[1]	(21,499)	$ 36,113	$ 10,797
Balance at end of period		99,457	117,306
Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL, LHFI			2,400
State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
PCL, LHFI			1,500
Allowance for Credit Losses, ACL [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		117,306	84,277	79,290
Loans charged-off		(10,275)	(11,475)	(14,481)
Recoveries		13,925	9,608	8,671
Net (charge-offs) recoveries		3,650	(1,867)	(5,810)
PCL, LHFI		(21,499)	36,113	10,797
Balance at end of period		99,457	117,306	84,277
Allowance for Credit Losses, ACL [Member] | Commercial and Industrial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		14,851	25,992
Loans charged-off		(4,391)	(1,557)
Recoveries		4,727	1,736
PCL, LHFI		3,752	(2,356)
Balance at end of period		18,939	14,851	25,992
Allowance for Credit Losses, ACL [Member] | Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,838	3,379
Loans charged-off		(1,640)	(2,039)
Recoveries		1,665	1,824
PCL, LHFI		(1,089)	615
Balance at end of period		4,774	5,838	3,379
Allowance for Credit Losses, ACL [Member] | State and Other Political Subdivision Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		3,190	2,229
PCL, LHFI		(482)	(1,494)
Balance at end of period		2,708	3,190	2,229
Allowance for Credit Losses, ACL [Member] | Other Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		7,439	5,303
Loans charged-off		(3,750)	(3,922)
Recoveries		4,024	3,929
PCL, LHFI		(2,365)	45
Balance at end of period		5,348	7,439	5,303
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		6,854	6,371
Loans charged-off		(39)	(12)
Recoveries		1,564	716
PCL, LHFI		(2,300)	(33)
Balance at end of period		6,079	6,854	6,371
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		9,928	5,888
Loans charged-off		(109)	(117)
Recoveries		505	378
PCL, LHFI		(14)	(409)
Balance at end of period		10,310	9,928	5,888
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		48,523	26,158
Loans charged-off		(169)	(3,777)
Recoveries		1,245	546
PCL, LHFI		(11,687)	33,775
Balance at end of period		37,912	48,523	26,158
Allowance for Credit Losses, ACL [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		7,382	4,024
Loans charged-off			(8)
Recoveries		20	68
PCL, LHFI		(2,689)	4,063
Balance at end of period		4,713	7,382	4,024
Allowance for Credit Losses, ACL [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		8,158	1,889
Recoveries		47	208
PCL, LHFI		(2,237)	2,859
Balance at end of period		5,968	8,158	1,889
Allowance for Credit Losses, ACL [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period		5,143	3,044
Loans charged-off		(177)	(43)
Recoveries		128	203
PCL, LHFI		(2,388)	(952)
Balance at end of period		$ 2,706	5,143	3,044
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
LHFI			(3,039)
Allowance for loan losses, acquired loans transfer			815
Acquired loans ACL adjustment			1,007
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			(1,217)
Balance at end of period				(1,217)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Commercial and Industrial Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			(8,964)
Balance at end of period				(8,964)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Consumer Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			2,059
Balance at end of period				2,059
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | State and Other Political Subdivision Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			2,455
Balance at end of period				2,455
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Commercial Loans [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			2,084
Balance at end of period				2,084
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Construction, Land Development and Other Land [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			(188)
Balance at end of period				(188)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Other Secured by 1-4 Family Residential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			4,188
Balance at end of period				4,188
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Secured by Nonfarm, Nonresidential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			(8,179)
Balance at end of period				(8,179)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Loans Secured by Real Estate [Member] | Other Real Estate Secured [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			(765)
Balance at end of period				(765)
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Loans Secured by Real Estate [Member] | Other Construction [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			3,202
Balance at end of period				3,202
Allowance for Credit Losses, ACL [Member] | ASU 2016-13 [Member] | Other Loans Secured by Real Estate [Member] | Secured by 1-4 Family Residential Properties [Member] | Cumulative Effect Period Of Adoption Adjustment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period			$ 2,891
Balance at end of period				$ 2,891

[1] Effective January 1, 2020, Trustmark adopted FASB ASU 2016-13 using the modified retrospective approach. Therefore, prior period balances are presented under legacy GAAP and may not be comparable to current period presentation.