Defined Benefit and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2015

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 Trustmark’s qualified defined benefit pension plans (Trustmark Capital Accumulation Plan and BancTrust Pension Plan) ($ in thousands):

	December 31,
	2015			2014
Change in benefit obligation:
Benefit obligation, beginning of year	$	101,904		$	128,974
Service cost		513			495
Interest cost		3,461			5,299
Actuarial (gain) loss		(2,807	)		11,675
Benefits paid for BancTrust Pension Plan		—			(38,853	)
Benefits paid for Trustmark Capital Accumulation Plan		(11,668	)		(7,041	)
Settlement loss from BancTrust termination		—			1,355
Benefit obligation, end of year	$	91,403		$	101,904
Change in plan assets:
Fair value of plan assets, beginning of year	$	86,287		$	126,142
Actual return on plan assets		(547	)		4,632
Employer contributions		65			1,407
Benefit payments for BancTrust Pension Plan		—			(38,853	)
Benefit payments for Trustmark Capital Accumulation Plan		(11,668	)		(7,041	)
Fair value of plan assets, end of year	$	74,137		$	86,287
Funded status at end of year - net liability	$	(17,266	)	$	(15,617	)
Amounts recognized in accumulated other comprehensive loss:
Net loss - amount recognized	$	24,927		$	28,100

Net Periodic Benefit Cost

	Years Ended December 31,
	2015			2014			2013
Net periodic benefit cost:
Service cost	$	513		$	495		$	595
Interest cost		3,461			5,299			4,758
Expected return on plan assets		(5,187	)		(6,245	)		(7,720	)
Recognized net loss due to BancTrust termination		—			1,355			—
Recognized net loss due to lump sum settlements		2,221			905			2,225
Recognized net actuarial (gain) loss		3,878			(283	)		5,516
Net periodic benefit cost	$	4,886		$	1,526		$	5,374
Other changes in plan assets and benefit obligation recognized in other    comprehensive income (loss), before taxes:
Net (gain) loss - Total recognized in other comprehensive income (loss)	$	(3,173	)	$	12,664		$	(29,742	)
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	1,713		$	14,190		$	(24,368	)
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		3.86	%		3.57	%		4.30	%
Discount rate for net periodic benefit cost		3.57	%		4.30	%		3.50	%
Expected long-term return on plan assets		7.00	%		7.50	%		7.50	%

Weighted-Average Asset Allocation

The weighted-average asset allocations by asset category for Trustmark’s qualified defined benefit pension plans at December 31, 2015 and 2014 are presented below.  Due to the termination and full distribution of the BancTrust Pension Plan during 2014, December 31, 2015 and 2014 includes only amounts related to the Trustmark Capital Accumulation Plan.

	December 31,
	2015			2014
Money market fund		3.6	%		8.7	%
Fixed income mutual funds		29.0	%		11.9	%
Equity mutual funds		16.1	%		72.2	%
Equity securities		51.3	%		7.0	%
Fixed income hedge fund		0.0	%		0.2	%
Total		100.0	%		100.0	%

Plan Assets Measured at Fair Value

The following table sets forth by level, within the fair value hierarchy, the qualified defined benefit pension plan’s assets measured at fair value at December 31, 2015 and 2014 ($ in thousands):

	December 31, 2015
	Total		Level 1		Level 2		Level 3
Money market fund	$	2,678	$	2,678	$	—	$	—
Fixed income mutual funds		21,472		21,472		—		—
Equity mutual funds		11,922		11,922		—		—
Equity securities		38,065		38,065		—		—
Total assets at fair value	$	74,137	$	74,137	$	—	$	—

	December 31,2014
	Total		Level 1		Level 2		Level 3
Money market fund	$	7,544	$	7,544	$	—	$	—
Fixed income mutual funds		10,267		10,267		—		—
Equity mutual funds		62,265		62,265		—		—
Equity securities		6,057		6,057		—		—
Fixed income hedge fund		154		—		—		154
Total assets at fair value	$	86,287	$	86,133	$	—	$	154

Changes in Fair Value of Plan Level Three Assets

The following table sets forth a summary of changes in fair value of the Level 3 plan assets for the years ended December 31, 2015 and 2014 ($ in thousands):

	Fixed Income Hedge Fund
Balance, January 1, 2014	$	163
Change in fair value		(9	)
Balance, December 31, 2014		154
Disposition		(154	)
Balance, December 31, 2015	$	—

Estimated Future Benefit Payments and Other Disclosures

The following table presents the expected benefit payments, which reflect expected future service, for Trustmark’s Capital Accumulation Plan ($ in thousands):

Year	Amount
2016	$	10,817
2017		8,082
2018		6,417
2019		6,158
2020		5,915
2021 - 2025		26,459

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 ($ in thousands):

	December 31,
	2015			2014
Change in benefit obligation:
Benefit obligation, beginning of year	$	59,744		$	52,489
Service cost		431			296
Interest cost		2,082			2,198
Actuarial (gain) loss		(1,702	)		7,392
Benefits paid		(2,789	)		(2,631	)
Benefit obligation, end of year	$	57,766		$	59,744
Change in plan assets:
Fair value of plan assets, beginning of year	$	—		$	—
Employer contributions		2,789			2,631
Benefit payments		(2,789	)		(2,631	)
Fair value of plan assets, end of year	$	—		$	—
Funded status at end of year - net liability	$	(57,766	)	$	(59,744	)
Amounts recognized in accumulated other comprehensive loss:
Net loss	$	18,548		$	21,242
Prior service cost		1,609			1,860
Amounts recognized	$	20,157		$	23,102

Net Periodic Benefit Cost

	Years Ended December 31,
	2015			2014			2013
Net periodic benefit cost:
Service cost	$	431		$	296		$	597
Interest cost		2,082			2,198			1,943
Amortization of prior service cost		250			250			250
Recognized net actuarial loss		992			661			1,038
Net periodic benefit cost	$	3,755		$	3,405		$	3,828
Other changes in plan assets and benefit obligation recognized in other    comprehensive income (loss), before taxes:
Net (gain) loss	$	(2,694	)	$	6,733		$	(5,224	)
Amortization of prior service cost		(250	)		(250	)		(250	)
Total recognized in other comprehensive income (loss)	$	(2,944	)	$	6,483		$	(5,474	)
Total recognized in net periodic benefit cost and other comprehensive    income (loss)	$	811		$	9,888		$	(1,646	)
Weighted-average assumptions as of end of year:
Discount rate for benefit obligation		3.86	%		3.57	%		4.30	%
Discount rate for net periodic benefit cost		3.57	%		4.30	%		3.50	%

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
2016	$	3,071
2017		3,462
2018		3,610
2019		3,683
2020		3,865
2021 - 2025		19,685