Shareholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2010 Trustmark Corporation [Member] Total Capital (to Risk Weighted Assets) [Member]		Sep. 30, 2011 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Dec. 31, 2010 Trustmark Corporation [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]		Sep. 30, 2011 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Dec. 31, 2010 Trustmark Corporation [Member] Tier 1 Capital (to Average Assets) [Member]		Sep. 30, 2011 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2010 Trustmark National Bank [Member] Total Capital (to Risk Weighted Assets) [Member]	Sep. 30, 2011 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Dec. 31, 2010 Trustmark National Bank [Member] Tier 1 Capital (to Risk Weighted Assets) [Member]	Sep. 30, 2011 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]	Dec. 31, 2010 Trustmark National Bank [Member] Tier 1 Capital (to Average Assets) [Member]
Total Capital (to Risk Weighted Assets) [Abstract]
Actual Regulatory Capital Amount			$ 1,094,402		$ 1,051,933										$ 1,054,986	$ 1,014,219
Actual Regulatory Capital Ratio (in hundredths)			16.78%		15.77%										16.38%	15.40%
Minimum Regulatory Capital Required Amount			521,797		533,774										515,396	526,894
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]									644,245	658,617
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							962,942		918,600								926,473	883,549
Actual Regulatory Capital Ratio (in hundredths)							14.76%		13.77%								14.38%	13.42%
Minimum Regulatory Capital Required Amount							260,899		266,887								257,698	263,447
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]							386,547	395,170
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											962,942		918,600						926,473	883,549
Actual Regulatory Capital Ratio (in hundredths)											10.38%		10.14%						10.12%	9.89%
Minimum Regulatory Capital Required Amount											278,202		271,867						274,523	267,967
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]					457,539	446,612
Minimum Regulatory Provision to be Well-Capitalized Ratio (in hundredths)												[1]		[1]					5.00%	5.00%
Other Comprehensive Income (Loss) before Tax [Abstract]
Accumulated other comprehensive income (loss), before tax	(18,469)	(2,596)
Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	46,696	17,711
Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	(91)	(2,228)
Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	3,649	2,771
Accumulated other comprehensive income (loss), before tax	31,785	15,658
Other Comprehensive Income (Loss), Tax [Abstract]
Accumulated other comprehensive income (loss), tax effect	7,043	972
Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Effect	(17,861)	(6,774)
Reclassification Adjustment for Sale of Securities Included in Net Income, Tax Effect	35	852
Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax Effect	(1,396)	(1,060)
Accumulated other comprehensive income (loss), tax effect	(12,179)	(6,010)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(11,426)	(1,624)
Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	28,835	10,937
Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(56)	(1,376)
Pension and Other Postretirement Benefit Plans, Net Unamortized (Gain) Loss Arising During Period, Net of Tax	2,253	1,711
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ 19,606	$ 9,648

[1] n/a