Defined Benefit and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2021

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,
	2021			2020
Change in benefit obligation:
Benefit obligation, beginning of year	$	9,547		$	9,060
Service cost		252			254
Interest cost		173			241
Actuarial (gain) loss		(198	)		876
Benefits paid		(1,127	)		(884	)
Benefit obligation, end of year	$	8,647		$	9,547
Change in plan assets:
Fair value of plan assets, beginning of year	$	2,873		$	3,443
Actual return on plan assets		291			(87	)
Employer contributions		863			401
Benefit payments		(1,127	)		(884	)
Fair value of plan assets, end of year	$	2,900		$	2,873
Funded status at end of year - net liability	$	(5,747	)	$	(6,674	)
Amounts recognized in accumulated other comprehensive loss:
Net loss - amount recognized	$	1,428		$	2,564
Actuarial (gain) loss included in benefit obligation:
Change in discount rate	$	(491	)	$	1,009
Change in mortality table		15			(47	)
Other		278			(86	)
Actuarial (gain) loss	$	(198	)	$	876

Net Periodic Benefit Cost

	Years Ended December 31,
	2021			2020			2019
Net periodic benefit cost:
Service cost	$	252		$	254		$	211
Interest cost		173			241			361
Expected return on plan assets		(130	)		(154	)		(202	)
Recognized net loss due to lump sum settlements		183			119			312
Recognized net actuarial loss		594			326			373
Net periodic benefit cost	$	1,072		$	786		$	1,055
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)	$	(1,136	)	$	671		$	(277	)
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	(64	)	$	1,457		$	778
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		2.41	%		1.95	%		2.84	%
Discount rate for net periodic benefit cost		1.95	%		2.84	%		3.97	%
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, 2021 and 2020.

	December 31,
	2021			2020
Money market fund		4.0	%		5.0	%
Exchange traded funds:
Equity securities		50.0	%		43.0	%
Fixed income		35.0	%		41.0	%
International		11.0	%		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, 2021 and 2020 ($ in thousands):

	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	$	—	$	—

	December 31, 2020
	Total		Level 1		Level 2		Level 3
Money market fund	$	131	$	131	$	—	$	—
Exchange traded funds:
Equity securities		1,242		1,242		—		—
Fixed income		1,182		1,182		—		—
International		318		318		—		—
Total assets at fair value	$	2,873	$	2,873	$	—	$	—

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
2022	$	1,275
2023		1,486
2024		1,145
2025		594
2026		641
2027 - 2031		2,138

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,
	2021			2020
Change in benefit obligation:
Benefit obligation, beginning of year	$	59,646		$	57,482
Service cost		75			77
Interest cost		1,125			1,576
Actuarial (gain) loss		(2,357	)		4,168
Benefits paid		(3,454	)		(3,657	)
Benefit obligation, end of year	$	55,035		$	59,646
Change in plan assets:
Fair value of plan assets, beginning of year	$	—		$	—
Employer contributions		3,454			3,657
Benefit payments		(3,454	)		(3,657	)
Fair value of plan assets, end of year	$	—		$	—
Funded status at end of year - net liability	$	(55,035	)	$	(59,646	)
Amounts recognized in accumulated other comprehensive loss:
Net loss	$	17,937		$	21,486
Prior service cost		348			459
Amounts recognized	$	18,285		$	21,945
Actuarial (gain) loss included in benefit obligation:
Change in discount rate	$	(2,431	)	$	4,997
Change in mortality table		134			(380	)
Other		(60	)		(449	)
Actuarial (gain) loss	$	(2,357	)	$	4,168

Net Periodic Benefit Cost

	Years Ended December 31,
	2021			2020			2019
Net periodic benefit cost:
Service cost	$	75		$	77		$	109
Interest cost		1,125			1,576			2,044
Amortization of prior service cost		111			150			250
Recognized net actuarial loss		1,192			957			627
Net periodic benefit cost	$	2,503		$	2,760		$	3,030
Other changes in plan assets and benefit obligation recognized in other    comprehensive income (loss), before taxes:
Net (gain) loss	$	(3,549	)	$	3,211		$	4,872
Amortization of prior service cost		(111	)		(150	)		(250	)
Total recognized in other comprehensive income (loss)	$	(3,660	)	$	3,061		$	4,622
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	(1,157	)	$	5,821		$	7,652
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		2.41	%		1.95	%		2.84	%
Discount rate for net periodic benefit cost		1.95	%		2.84	%		3.97	%

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
2022	$	4,065
2023		3,978
2024		3,967
2025		3,801
2026		3,742
2027 - 2031		16,941