Shareholders' Equity (Tables)

9 Months Ended

Sep. 30, 2023

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 September 30, 2023 and December 31, 2022 ($ in thousands):

	Actual
	Regulatory Capital					Minimum			To Be Well
	Amount		Ratio			Requirement			Capitalized
At September 30, 2023:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,498,217		9.89	%		7.00	%	n/a
Trustmark National Bank		1,579,132		10.43	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,558,217		10.29	%		8.50	%	n/a
Trustmark National Bank		1,579,132		10.43	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,834,295		12.11	%		10.50	%	n/a
Trustmark National Bank		1,731,783		11.44	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,558,217		8.49	%		4.00	%	n/a
Trustmark National Bank		1,579,132		8.63	%		4.00	%		5.00	%
At December 31, 2022:
Common Equity Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,413,672		9.74	%		7.00	%	n/a
Trustmark National Bank		1,501,889		10.34	%		7.00	%		6.50	%
Tier 1 Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,473,672		10.15	%		8.50	%	n/a
Trustmark National Bank		1,501,889		10.34	%		8.50	%		8.00	%
Total Capital (to Risk Weighted Assets)
Trustmark Corporation	$	1,729,499		11.91	%		10.50	%	n/a
Trustmark National Bank		1,634,454		11.26	%		10.50	%		10.00	%
Tier 1 Leverage (to Average Assets)
Trustmark Corporation	$	1,473,672		8.47	%		4.00	%	n/a
Trustmark National Bank		1,501,889		8.65	%		4.00	%		5.00	%

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

The following tables present 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).

	Nine Months Ended September 30, 2023									Nine Months Ended September 30, 2022
	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	$	(16,062	)	$	4,246		$	(11,816	)	$	(314,517	)	$	78,630		$	(235,887	)
Change in net unrealized holding loss on    securities transferred to held to maturity		11,799			(2,950	)		8,849			(31,451	)		7,863			(23,588	)
Total securities available for sale    and transferred securities		(4,263	)		1,296			(2,967	)		(345,968	)		86,493			(259,475	)
Pension and other postretirement benefit plans:
Reclassification adjustments for changes    realized in net income:
Net change in prior service costs		83			(21	)		62			83			(21	)		62
Recognized net loss due to lump sum    settlements		25			(6	)		19			—			—			—
Change in net actuarial loss		216			(54	)		162			914			(228	)		686
Total pension and other postretirement    benefit plans		324			(81	)		243			997			(249	)		748
Cash flow hedge derivatives:
Change in accumulated gain (loss) on effective    cash flow hedge derivatives		(24,569	)		6,142			(18,427	)		(19,524	)		4,881			(14,643	)
Reclassification adjustment for (gain) loss realized    in net income		11,555			(2,889	)		8,666			(643	)		161			(482	)
Total cash flow hedge derivatives		(13,014	)		3,253			(9,761	)		(20,167	)		5,042			(15,125	)
Total other comprehensive income (loss)	$	(16,953	)	$	4,468		$	(12,485	)	$	(365,138	)	$	91,286		$	(273,852	)

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, 2023	$	(254,442	)	$	(5,792	)	$	(15,169	)	$	(275,403	)
Other comprehensive income (loss) before reclassification		(2,967	)		—			(18,427	)		(21,394	)
Amounts reclassified from accumulated other    comprehensive income (loss)		—			243			8,666			8,909
Net other comprehensive income (loss)		(2,967	)		243			(9,761	)		(12,485	)
Balance at September 30, 2023	$	(257,409	)	$	(5,549	)	$	(24,930	)	$	(287,888	)
Balance at January 1, 2022	$	(17,774	)	$	(14,786	)	$	—		$	(32,560	)
Other comprehensive income (loss) before reclassification		(259,475	)		—			(14,643	)		(274,118	)
Amounts reclassified from accumulated other    comprehensive income (loss)		—			748			(482	)		266
Net other comprehensive income (loss)		(259,475	)		748			(15,125	)		(273,852	)
Balance at September 30, 2022	$	(277,249	)	$	(14,038	)	$	(15,125	)	$	(306,412	)