Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Securities Available for Sale and Transferred Securities [Member]	Mar. 31, 2013 Securities Available for Sale and Transferred Securities [Member]	Mar. 31, 2014 Defined Benefit Pension Items [Member]	Mar. 31, 2013 Defined Benefit Pension Items [Member]	Mar. 31, 2014 Gains on Cash Flow Hedge [Member]	Mar. 31, 2013 Gains on Cash Flow Hedge [Member]	Mar. 31, 2014 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2013 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Mar. 31, 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]		Mar. 31, 2014 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Dec. 31, 2013 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Mar. 31, 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]	Mar. 31, 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]	Mar. 31, 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									$ 1,149,286		$ 1,122,904										$ 1,125,674	$ 1,076,391
Actual Regulatory Capital Ratio (in hundredths)									14.34%		14.18%										14.07%	13.74%
Minimum Regulatory Capital Required Amount									641,319		633,310										640,125	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]									800,156	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													1,051,263		1,026,858								1,029,171	982,925
Actual Regulatory Capital Ratio (in hundredths)													13.11%		12.97%								12.86%	12.55%
Minimum Regulatory Capital Required Amount													320,659		316,655								320,062	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]							480,094	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																	1,051,263		1,026,858						1,029,171	982,925
Actual Regulatory Capital Ratio (in hundredths)																	9.14%		9.06%						8.97%	8.76%
Minimum Regulatory Capital Required Amount																	459,907		453,487						459,183	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]					573,979	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	6,848	2,234
Reclassification adjustment for net gains realized in net income, Before tax amount	(389)	(204)
Change in net unrealized holding loss on securities transferred to held to maturity, Before tax amount	1,333
Total securities available for sale and transferred securities, Before tax amount	7,792	2,030
Securities available for sale and transferred securities, Tax (expense) benefit: [Abstract]
Unrealized holding (losses) gains arising during period, Tax Effect	(2,619)	(854)
Reclassification adjustment for net gains realized in net income, Tax	149	78
Change in net unrealized holding loss on securities transferred to held to maturity, Tax	(510)
Total securities available for sale and transferred securities, Tax	(2,980)	(776)
Securities available for sale and transferred securities, Net of tax amount: [Abstract]
Unrealized holding (losses) gains arising during the period, after tax income (expense)	4,229	1,380
Reclassification adjustment for net gains realized in net income, after tax income (expense)	(240)	(126)
Change in net unrealized holding loss on securities transferred to held to maturity, after tax income (expense)	823	0
Total securities available for sale and transferred securities, after tax income (expense)	4,812	1,254
Pension and other postretirement benefit plans, Before tax amount: [Abstract]
Net change in prior service costs, before tax amount	63	63
Recognized net loss due to Settlement, before tax amount	375
Recognized net actuarial loss (gain), before tax amount	906	1,654
Total pension and other postretirement benefit plans, before tax amount	1,344	1,717
Pension and other postretirement benefit plans, Tax (expense) benefit: [Abstract]
Net change in prior service costs, tax (expense) benefit	(24)	(24)
Recognized net loss due to settlement, tax (expense) benefit	(143)
Recognized net actuarial loss (gain), tax (expense) benefit	(347)	(633)
Total pension and other postretirement benefit plans, tax (expense) benefit	(514)	(657)
Pension and other postretirement benefit plans, Net of tax amount: [Abstract]
Net change in prior service costs, after tax income (expense)	39	39
Recognized net loss due to settlement after tax income (expense)	232
Recognized net actuarial loss (gain), after tax income (expense)	559	1,021
Total pension and other postretirement benefit plans, after tax income (expense)	830	1,060
Derivatives, Before tax amount: [Abstract]
Change in accumulated gain on effective cash flow hedge derivatives, before tax amount	(661)
Derivatives, Tax (expense) benefit: [Abstract]
Change in accumulated gain on effective cash flow hedge derivatives, tax (expense) benefit	253
Derivatives, Net of tax amount: [Abstract]
Change in the accumulated gain on effective cash flow hedge derivatives, after tax amount	(408)	0
Total other comprehensive income (loss), Before tax amount	8,475	3,747
Total other comprehensive income (loss), Tax expense (benefit)	(3,241)	(1,433)
Total other comprehensive income (loss), Net of tax	5,234	2,314
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	5,474	2,440	5,052	1,380	830	1,060	(408)	0
Amounts reclassified from accumulated other comprehensive income	(240)	(126)	(240)	(126)	0	0	0	0
Net other comprehensive income (loss)	5,234	2,314	4,812	1,254	830	1,060	(408)	0
Ending balance	$ (38,497)	$ 5,709	$ (20,650)	$ 46,189	$ (18,963)	$ (40,480)	$ 1,116	$ 0

[1] n/a