Defined Benefit and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2022

Trustmark Capital Accumulation Plan [Member]

Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]

Plan Benefit Obligation, Plan Assets and Funded Status of the Plan

The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for the Continuing Plan for the periods presented ($ in thousands):

	December 31,
	2022			2021
Change in benefit obligation:
Benefit obligation, beginning of year	$	8,647		$	9,547
Service cost		115			252
Interest cost		192			173
Actuarial (gain) loss		(1,882	)		(198	)
Benefits paid		(165	)		(1,127	)
Benefit obligation, end of year	$	6,907		$	8,647
Change in plan assets:
Fair value of plan assets, beginning of year	$	2,900		$	2,873
Actual return on plan assets		(285	)		291
Employer contributions		457			863
Benefit payments		(165	)		(1,127	)
Fair value of plan assets, end of year	$	2,907		$	2,900
Funded status at end of year - net liability	$	(4,000	)	$	(5,747	)
Amounts recognized in accumulated other comprehensive loss:
Net (gain) loss - amount recognized	$	(271	)	$	1,428
Actuarial (gain) loss included in benefit obligation:
Change in discount rate	$	(2,174	)	$	(491	)
Change in mortality table		—			15
Other		292			278
Actuarial (gain) loss	$	(1,882	)	$	(198	)

Net Periodic Benefit Cost

	Years Ended December 31,
	2022			2021			2020
Net periodic benefit cost:
Service cost	$	115		$	252		$	254
Interest cost		192			173			241
Expected return on plan assets		(121	)		(130	)		(154	)
Recognized net loss due to lump sum settlements		—			183			119
Recognized net actuarial loss		224			594			326
Net periodic benefit cost	$	410		$	1,072		$	786
Other changes in plan assets and benefit obligation recognized in other    comprehensive income (loss), before taxes:
Net loss - Total recognized in other comprehensive income (loss)	$	(1,699	)	$	(1,136	)	$	671
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	(1,289	)	$	(64	)	$	1,457
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		4.88	%		2.41	%		1.95	%
Discount rate for net periodic benefit cost		2.41	%		1.95	%		2.84	%
Expected long-term return on plan assets		5.00	%		5.00	%		5.00	%

Weighted-Average Asset Allocation

The weighted-average asset allocations by asset category are presented below for the Continuing Plan at December 31, 2022 and 2021.

	December 31,
	2022			2021
Money market fund		7.0	%		4.0	%
Exchange traded funds:
Equity securities		47.0	%		50.0	%
Fixed income		39.0	%		35.0	%
International		7.0	%		11.0	%
Total		100.0	%		100.0	%

Plan Assets Measured at Fair Value

The following tables set forth by level, within the fair value hierarchy, the Continuing Plan’s assets measured at fair value at December 31, 2022 and 2021 ($ in thousands):

	December 31, 2022
	Total		Level 1		Level 2		Level 3
Money market fund	$	203	$	203	$	—	$	—
Exchange traded funds:
Equity securities		1,379		1,379		—		—
Fixed income		1,135		1,135		—		—
International		190		190		—		—
Total assets at fair value	$	2,907	$	2,907	$	—	$	—

	December 31, 2021
	Total		Level 1		Level 2		Level 3
Money market fund	$	107	$	107	$	—	$	—
Exchange traded funds:
Equity securities		1,460		1,460		—		—
Fixed income		1,021		1,021		—		—
International		312		312		—		—
Total assets at fair value	$	2,900	$	2,900	$	—	$	—

Estimated Future Benefit Payments and Other Disclosures

The following table presents the expected benefit payments, which reflect expected future service, for the Continuing Plan ($ in thousands):

Year	Amount
2023	$	1,864
2024		1,068
2025		556
2026		583
2027		639
2028 - 2032		1,565

Supplemental Retirement Plan [Member]

Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]

Plan Benefit Obligation, Plan Assets and Funded Status of the Plan

The following tables present information regarding the benefit obligation, plan assets, funded status, amounts recognized in accumulated other comprehensive loss, net periodic benefit cost and other statistical disclosures for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands):

	December 31,
	2022			2021
Change in benefit obligation:
Benefit obligation, beginning of year	$	55,035		$	59,646
Service cost		71			75
Interest cost		1,278			1,125
Actuarial (gain) loss		(9,195	)		(2,357	)
Benefits paid		(3,988	)		(3,454	)
Benefit obligation, end of year	$	43,201		$	55,035
Change in plan assets:
Fair value of plan assets, beginning of year	$	—		$	—
Employer contributions		3,988			3,454
Benefit payments		(3,988	)		(3,454	)
Fair value of plan assets, end of year	$	—		$	—
Funded status at end of year - net liability	$	(43,201	)	$	(55,035	)
Amounts recognized in accumulated other comprehensive loss:
Net loss	$	7,756		$	17,937
Prior service cost		237			348
Amounts recognized	$	7,993		$	18,285
Actuarial (gain) loss included in benefit obligation:
Change in discount rate	$	(9,803	)	$	(2,431	)
Change in mortality table		—			134
Other		608			(60	)
Actuarial (gain) loss	$	(9,195	)	$	(2,357	)

Net Periodic Benefit Cost

	Years Ended December 31,
	2022			2021			2020
Net periodic benefit cost:
Service cost	$	71		$	75		$	77
Interest cost		1,278			1,125			1,576
Amortization of prior service cost		111			111			150
Recognized net actuarial loss		986			1,192			957
Net periodic benefit cost	$	2,446		$	2,503		$	2,760
Other changes in plan assets and benefit obligation recognized in other    comprehensive income (loss), before taxes:
Net (gain) loss	$	(10,181	)	$	(3,549	)	$	3,211
Amortization of prior service cost		(111	)		(111	)		(150	)
Total recognized in other comprehensive income (loss)	$	(10,292	)	$	(3,660	)	$	3,061
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	(7,846	)	$	(1,157	)	$	5,821
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		4.88	%		2.41	%		1.95	%
Discount rate for net periodic benefit cost		2.41	%		1.95	%		2.84	%

Estimated Future Benefit Payments and Other Disclosures

The following table presents the expected benefits payments for Trustmark’s supplemental retirement plans ($ in thousands):

Year	Amount
2023	$	3,963
2024		3,977
2025		3,838
2026		3,785
2027		3,596
2028 - 2032		16,536