Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2012 Reclassification out of Accumulated Other Comprehensive Income [Member]	Jun. 30, 2013 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2012 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Jun. 30, 2013 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2012 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Jun. 30, 2013 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Dec. 31, 2012 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Jun. 30, 2013 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2012 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Jun. 30, 2013 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2012 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Jun. 30, 2013 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]	Dec. 31, 2012 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount							$ 1,094,442		$ 1,157,838										$ 1,054,209	$ 1,119,438
Actual Regulatory Capital Ratio (in hundredths)							13.89%		17.22%										13.52%	16.85%
Minimum Regulatory Capital Required Amount							630,262		537,861										623,621	531,577
Minimum Regulatory Capital Required Ratio (in hundredths)							8.00%		8.00%										8.00%	8.00%
Minimum Regulatory Provision to be Well-Capitalized Amount								[1]		[1]									779,526	664,472
Minimum Regulatory Provision to be Well-Capitalized Ratio (in hundredths)								[1]		[1]									10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount											988,994		1,043,865								951,313	1,007,775
Actual Regulatory Capital Ratio (in hundredths)											12.55%		15.53%								12.20%	15.17%
Minimum Regulatory Capital Required Amount											315,131		268,930								311,811	265,789
Minimum Regulatory Capital Required Ratio (in hundredths)											4.00%		4.00%								4.00%	4.00%
Minimum Regulatory Provision to be Well-Capitalized Amount												[1]		[1]							467,716	398,683
Minimum Regulatory Provision to be Well-Capitalized Ratio (in hundredths)												[1]		[1]							6.00%	6.00%
Tier 1 Capital (to Average Assets) [Abstract]
Actual Regulatory Capital Amount															988,994		1,043,865						951,313	1,007,775
Actual Regulatory Capital Ratio (in hundredths)															8.71%		10.97%						8.47%	10.72%
Minimum Regulatory Capital Required Amount															340,462		285,556						336,848	281,984
Minimum Regulatory Capital Required Ratio (in hundredths)															3.00%		3.00%						3.00%	3.00%
Minimum Regulatory Provision to be Well-Capitalized Amount																[1]		[1]					561,414	469,974
Minimum Regulatory Provision to be Well-Capitalized Ratio (in hundredths)																[1]		[1]					5.00%	5.00%
Before-Tax Amount [Abstract]
Accumulated other comprehensive income (loss), Before - Tax, balance			5,533	5,089
Unrealized holding losses on AFS arising during period, Before - Tax			(69,854)	(1,270)
Adjustment for net gains realized in net income, Before - Tax			(378)	(1,042)	378	1,042
Pension and other postretirement benefit plans, Before - Tax			3,937	3,174	3,937	3,174
Change in accumulated gain on effective cash flow hedge derivatives			2,355
Accumulated other comprehensive income (loss), Before - Tax, balance	(58,407)	5,951	(58,407)	5,951
Tax Effect [Abstract]
Accumulated other comprehensive income (loss), Tax Effect, balance			(2,138)	(1,968)
Unrealized holding (gain) losses arising during period, Tax Effect			26,719	486
Adjustment for net gains realized in net income, Tax Effect			145	399	145	399
Pension and other postretirement benefit plans, Tax Effect, balance			(1,506)	(1,214)
Change in accumulated gain on effective cash flow hedge derivatives			(901)
Accumulated other comprehensive income (loss), Tax Effect	22,319	(2,297)	22,319	(2,297)
Accumulated Other Comprehensive Income (Loss) [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax, balance			3,395	3,121
Unrealized holding (gain) losses arising during period	(44,515)	1,132	(43,135)	(784)
Adjustment for net gains realized in net income	(107)	5	(233)	(643)	(233)	(643)
Pension and other postretirement benefit plans	1,371	980	2,431	1,960
Change in accumulated gain on effective cash flow hedge derivatives	1,454	0	1,454	0
Accumulated Other Comprehensive Income, (Loss) Net of Tax, balance	(36,088)	3,654	(36,088)	3,654
Securities available for sale:
Reclassification adjustment for net gains realized in net income, pre-tax income (expense)			(378)	(1,042)	378	1,042
Reclassification adjustment for net gains realized in net income, tax (expense) benefit			(145)	(399)	(145)	(399)
Reclassification adjustment for net gains realized in net income, after tax income (expense)	107	(5)	233	643	233	643
Pension and other postretirement benefit plans:
Amortization of prior service cost, pre-tax income (expense)					(126)	(125)
Recognized net loss due to Settlement					(525)
Recognized net actuarial loss, pre-tax income (expense)					(3,286)	(3,049)
Total pension and other postretirement benefit plans, pre-tax income (expense)			(3,937)	(3,174)	(3,937)	(3,174)
Amortization of prior service cost, tax (expense) benefit					48	48
Recognized net loss due to settlement, tax benefit					201
Recognized net actuarial loss, tax (expense) benefit					1,257	1,166
Total pension and other postretirement benefit plans, tax (expense) benefit					1,506	1,214
Amortization of prior service cost, after tax income (expense)					(78)	(77)
Recognized net loss due to settlement after tax income (expense)					(324)
Recognized net actuarial loss, after tax income (expense)					(2,029)	(1,883)
Total pension and other postretirement benefit plans, after tax income (expense)					$ (2,431)	$ (1,960)

[1] n/a