Defined Benefit and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2018

Trustmark Capital Accumulation Plan [Member]

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

Net Periodic Benefit Cost for Plan and Continuing Plan

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2018			2017			2018			2017
Service cost	$	69		$	64		$	208		$	190
Interest cost		83			102			249			1,394
Expected return on plan assets		(57	)		(51	)		(171	)		(267	)
Recognized net loss due to lump sum settlements		41			—			121			—
Recognized net loss due to defined benefit plan termination		—			—			—			17,644
Recognized net actuarial loss		143			142			428			1,272
Net periodic benefit cost	$	279		$	257		$	835		$	20,233

Supplemental Retirement Plan [Member]

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

Net Periodic Benefit Cost for Plan and Continuing Plan

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,
	2018		2017		2018		2017
Service cost	$	29	$	36	$	87	$	106
Interest cost		457		514		1,409		1,589
Amortization of prior service cost		63		63		188		188
Recognized net actuarial loss		218		214		664		651
Net periodic benefit cost	$	767	$	827	$	2,348	$	2,534