Defined Benefit and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2017

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 June 30,						Six Months Ended June 30,
	2017			2016			2017			2016
Service cost	$	63		$	108		$	126		$	216
Interest cost		627			830			1,292			1,660
Expected return on plan assets		(108	)		(1,022	)		(216	)		(2,044	)
Recognized net loss due to lump sum settlements		—			2,248			—			2,671
Recognized net loss due to defined benefit plan termination		17,644			—			17,644			—
Recognized net actuarial loss		565			660			1,130			1,321
Net periodic benefit cost	$	18,791		$	2,824		$	19,976		$	3,824

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 June 30,				Six Months Ended June 30,
	2017		2016		2017		2016
Service cost	$	35	$	74	$	70	$	148
Interest cost		514		542		1,075		1,088
Amortization of prior service cost		62		62		125		125
Recognized net actuarial loss		215		214		437		435
Net periodic benefit cost	$	826	$	892	$	1,707	$	1,796