LHFI and ACL, LHFI - Additional Information (Details 2)		12 Months Ended
		Dec. 31, 2021 USD ($) KeyRatio	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Financing Receivable Recorded Investment [Line Items]
Number of key quality ratios | KeyRatio		6
Exposure for commercial non accrual loans to be reviewed on individual basis		$ 500,000
Exposure for commercial accrual loans deemed to be reviewed on individual basis		500,000
LHFS past due 90 days or more		$ 69,900,000	$ 119,400,000
Number of days used as baseline in evaluating collateral documentation exceptions for loan policy		90 days
Financing Receivable [Abstract]
PCL	[1]	$ (21,499,000)	36,113,000	$ 10,797,000
Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
PCL		(21,499,000)	36,113,000	$ 10,797,000
Commercial and Industrial Loans [Member]
Financing Receivable [Abstract]
PCL			2,400,000
Commercial and Industrial Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
PCL		3,752,000	(2,356,000)
State and Other Political Subdivision Loans [Member]
Financing Receivable [Abstract]
PCL			1,500,000
State and Other Political Subdivision Loans [Member] | Allowance for Credit Losses, ACL [Member]
Financing Receivable [Abstract]
PCL		(482,000)	$ (1,494,000)
Minimum [Member]
Financing Receivable [Abstract]
Credit amount used as baseline in evaluating loan policy		$ 100,000

[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.