Defined Benefit and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2025

Trustmark Capital Accumulation Plan [Member]

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

Net Periodic Benefit Cost

The following table presents information regarding the net periodic benefit cost for the Continuing Plan for the periods presented ($ in thousands):

	Three Months Ended September 30,						Nine Months Ended September 30,
	2025			2024			2025			2024
Service cost	$	9		$	10		$	27		$	30
Interest cost		68			62			206			185
Expected return on plan assets		(31	)		(24	)		(94	)		(72	)
Recognized net (gain) loss due to lump sum settlements		(29	)		—			(79	)		(13	)
Recognized net actuarial (gain) loss		(1	)		—			(5	)		—
Net periodic benefit cost	$	16		$	48		$	55		$	130

Supplemental Retirement Plan [Member]

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

Net Periodic Benefit Cost

The following table presents information regarding the net periodic benefit cost for Trustmark’s nonqualified supplemental retirement plans for the periods presented ($ in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2025		2024		2025		2024
Service cost	$	3	$	11	$	11	$	33
Interest cost		476		457		1,446		1,393
Amortization of prior service cost		4		28		11		83
Recognized net actuarial loss		62		84		198		263
Net periodic benefit cost	$	545	$	580	$	1,666	$	1,772