Shareholders' Equity (Tables)

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Table of Actual Regulatory Capital Amounts and Ratios

The following table provides Trustmark’s and TNB’s actual regulatory capital amounts and ratios under regulatory capital standards in effect at March 31, 2024 and December 31, 2023 ($ in thousands):

	Actual
	Regulatory Capital					Minimum			To Be Well
	Amount		Ratio			Requirement			Capitalized
At March 31, 2024:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,543,460		10.12	%		7.00	%	n/a
Trustmark National Bank		1,620,495		10.62	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,603,460		10.51	%		8.50	%	n/a
Trustmark National Bank		1,620,495		10.62	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,895,697		12.42	%		10.50	%	n/a
Trustmark National Bank		1,789,195		11.73	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,603,460		8.76	%		4.00	%	n/a
Trustmark National Bank		1,620,495		8.87	%		4.00	%		5.00	%
At December 31, 2023:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,521,665		10.04	%		7.00	%	n/a
Trustmark National Bank		1,602,327		10.58	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,581,665		10.44	%		8.50	%	n/a
Trustmark National Bank		1,602,327		10.58	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,862,246		12.29	%		10.50	%	n/a
Trustmark National Bank		1,759,426		11.61	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,581,665		8.62	%		4.00	%	n/a
Trustmark National Bank		1,602,327		8.75	%		4.00	%		5.00	%

Net Change in Components of Accumulated Other Comprehensive Income (Loss) and the Related Tax Effects

The following table presents the net change in the components of accumulated other comprehensive income (loss) and the related tax effects allocated to each component for the periods presented ($ in thousands).

	Three Months Ended March 31, 2024									Three Months Ended March 31, 2023
	Before Tax Amount			Tax (Expense) Benefit			Net of Tax Amount			Before Tax Amount		Tax (Expense) Benefit			Net of Tax Amount
Securities available for sale and transferred securities:
Net unrealized holding gains (losses) arising    during the period	$	(2,552	)	$	638		$	(1,914	)	$	30,534	$	(7,404	)	$	23,130
Change in net unrealized holding loss on    securities transferred to held to maturity		3,661			(915	)		2,746			3,859		(965	)		2,894
Total securities available for sale    and transferred securities		1,109			(277	)		832			34,393		(8,369	)		26,024
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		28			(7	)		21			28		(7	)		21
Recognized net loss due to lump sum    settlements		—			—			—			25		(6	)		19
Change in net actuarial loss		95			(24	)		71			77		(19	)		58
Total pension and other postretirement    benefit plans		123			(31	)		92			130		(32	)		98
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		(15,960	)		3,990			(11,970	)		6,269		(1,567	)		4,702
Reclassification adjustment for (gain) loss realized    in net income		4,820			(1,205	)		3,615			2,931		(733	)		2,198
Total cash flow hedge derivatives		(11,140	)		2,785			(8,355	)		9,200		(2,300	)		6,900
Total other comprehensive income (loss)	$	(9,908	)	$	2,477		$	(7,431	)	$	43,723	$	(10,701	)	$	33,022

Summary of Changes in Balances of Accumulated Other Comprehensive Income (Loss)

The following table presents the changes in the balances of each component of accumulated other comprehensive income (loss) for the periods presented ($ in thousands). All amounts are presented net of tax.

	Securities Available for Sale and Transferred Securities			Defined Benefit Pension Items			Cash Flow Hedge Derivatives			Total
Balance at January 1, 2024	$	(204,670	)	$	(6,075	)	$	(8,978	)	$	(219,723	)
Other comprehensive income (loss) before reclassification		832			—			(11,970	)		(11,138	)
Amounts reclassified from accumulated other    comprehensive income (loss)		—			92			3,615			3,707
Net other comprehensive income (loss)		832			92			(8,355	)		(7,431	)
Balance at March 31, 2024	$	(203,838	)	$	(5,983	)	$	(17,333	)	$	(227,154	)
Balance at January 1, 2023	$	(254,442	)	$	(5,792	)	$	(15,169	)	$	(275,403	)
Other comprehensive income (loss) before reclassification		26,024			—			4,702			30,726
Amounts reclassified from accumulated other    comprehensive income (loss)		—			98			2,198			2,296
Net other comprehensive income (loss)		26,024			98			6,900			33,022
Balance at March 31, 2023	$	(228,418	)	$	(5,694	)	$	(8,269	)	$	(242,381	)