Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 Securities Available for Sale and Transferred Securities [Member]	Jun. 30, 2013 Securities Available for Sale and Transferred Securities [Member]	Jun. 30, 2014 Defined Benefit Pension Items [Member]	Jun. 30, 2013 Defined Benefit Pension Items [Member]	Jun. 30, 2014 Cash Flow Hedge Derivatives [Member]	Jun. 30, 2013 Cash Flow Hedge Derivatives [Member]	Jun. 30, 2014 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2013 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Jun. 30, 2014 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2013 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Jun. 30, 2014 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Dec. 31, 2013 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Jun. 30, 2014 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2013 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Jun. 30, 2014 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2013 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Jun. 30, 2014 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]	Dec. 31, 2013 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount											$ 1,188,748		$ 1,122,904										$ 1,165,481	$ 1,076,391
Actual Regulatory Capital Ratio (in hundredths)											14.54%		14.18%										14.28%	13.74%
Minimum Regulatory Capital Required Amount											654,050		633,310										652,784	626,672
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]									815,981	783,340
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															1,090,953		1,026,858								1,069,227	982,925
Actual Regulatory Capital Ratio (in hundredths)															13.34%		12.97%								13.10%	12.55%
Minimum Regulatory Capital Required Amount															327,025		316,655								326,392	313,336
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]							489,588	470,004
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																			1,090,953		1,026,858						1,069,227	982,925
Actual Regulatory Capital Ratio (in hundredths)																			9.43%		9.06%						9.25%	8.76%
Minimum Regulatory Capital Required Amount																			462,861		453,487						462,214	448,665
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]					577,767	560,831
Minimum Regulatory Provision to be Well-Capitalized Ratio (in hundredths)																				[1]		[1]					5.00%	5.00%
Securities available for sale and transferred securities, Before tax amount: [Abstract]
Unrealized holding (losses) gains arising during the period, Before tax amount			17,807	(69,854)
Reclassification adjustment for net gains realized in net income, Before tax amount			(389)	(378)
Change in net unrealized holding loss on securities transferred to held to maturity, Before tax amount			2,806
Total securities available for sale and transferred securities, Before tax amount			20,224	(70,232)
Securities available for sale and transferred securities, Tax (expense) benefit: [Abstract]
Unrealized holding (losses) gains arising during period, Tax Effect			(6,811)	26,719
Reclassification adjustment for net gains realized in net income, Tax			149	145
Change in net unrealized holding loss on securities transferred to held to maturity, Tax			(1,073)
Total securities available for sale and transferred securities, Tax			(7,735)	26,864
Securities available for sale and transferred securities, Net of tax amount: [Abstract]
Unrealized holding (losses) gains arising during the period, after tax income (expense)	6,767	(44,515)	10,996	(43,135)
Reclassification adjustment for net gains realized in net income, after tax income (expense)	0	(107)	(240)	(233)
Change in net unrealized holding loss on securities transferred to held to maturity, after tax income (expense)	910	0	1,733	0
Total securities available for sale and transferred securities, after tax income (expense)			12,489	(43,368)
Pension and other postretirement benefit plans, Before tax amount: [Abstract]
Net change in prior service costs, before tax amount			125	126
Recognized net loss due to Settlement, before tax amount			750	525
Recognized net actuarial loss (gain), before tax amount			1,805	3,286
Total pension and other postretirement benefit plans, before tax amount			2,680	3,937
Pension and other postretirement benefit plans, Tax (expense) benefit: [Abstract]
Net change in prior service costs, tax (expense) benefit			(48)	(48)
Recognized net loss due to settlement, tax (expense) benefit			(287)	(201)
Recognized net actuarial loss (gain), tax (expense) benefit			(690)	(1,257)
Total pension and other postretirement benefit plans, tax (expense) benefit			(1,025)	(1,506)
Pension and other postretirement benefit plans, Net of tax amount: [Abstract]
Net change in prior service costs, after tax income (expense)	38	39	77	78
Recognized net loss due to settlement after tax income (expense)	231	324	463	324
Recognized net actuarial loss (gain), after tax income (expense)	556	1,008	1,115	2,029
Total pension and other postretirement benefit plans, after tax income (expense)			1,655	2,431
Derivatives, Before tax amount: [Abstract]
Change in accumulated gain on effective cash flow hedge derivatives, before tax amount			(1,571)	2,355
Derivatives, Tax (expense) benefit: [Abstract]
Change in accumulated gain on effective cash flow hedge derivatives, tax (expense) benefit			601	(901)
Derivatives, Net of tax amount: [Abstract]
Change in the accumulated gain on effective cash flow hedge derivatives, after tax amount	(562)	1,454	(970)	1,454
Total other comprehensive income (loss), Before tax amount			21,333	(63,940)
Total other comprehensive income (loss), Tax expense (benefit)			(8,159)	24,457
Total other comprehensive income (loss), Net of tax			13,174	(39,483)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Opening balance			(43,731)	3,395	(25,462)	44,935	(19,793)	(41,540)	1,524	0
Other comprehensive income (loss) before reclassification			13,414	(39,250)	12,729	(43,135)	1,655	2,431	(970)	1,454
Amounts reclassified from accumulated other comprehensive income			(240)	(233)	(240)	(233)	0	0	0	0
Net other comprehensive income (loss)	7,940	(41,797)	13,174	(39,483)	12,489	(43,368)	1,655	2,431	(970)	1,454
Ending balance	$ (30,557)	$ (36,088)	$ (30,557)	$ (36,088)	$ (12,973)	$ 1,567	$ (18,138)	$ (39,109)	$ 554	$ 1,454

[1] n/a