Parent Company Only Financial Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Assets [Abstract]
Other assets	$ 322,837,000	$ 355,159,000
Total Assets	9,727,007,000	9,553,902,000
Liabilities and Shareholders' Equity: [Abstract]
Junior subordinated debt securities	61,856,000	61,856,000
Shareholders' equity	1,215,037,000	1,149,484,000	1,110,060,000	1,178,466,000
Total Liabilities and Shareholders' Equity	9,727,007,000	9,553,902,000
Expense: [Abstract]
Interest expense	43,036,000	56,195,000	87,853,000
Net Income	106,841,000	100,636,000	93,047,000
Preferred stock dividends			11,288,000
Accretion of discount on preferred stock	0	0	9,874,000
Net Income Available to Common Shareholders	106,841,000	100,636,000	73,049,000
Operating Activities: [Abstract]
Net income	106,841,000	100,636,000	93,047,000
Adjustments to reconcile net income to net cash provided by operating activities:
Other	30,713,000	29,087,000	5,657,000
Net cash provided by operating activities	173,589,000	206,778,000	172,317,000
Investing Activities: [Abstract]
Proceeds from maturities of securities available for sale	749,149,000	650,419,000	388,781,000
Purchases of securities available for sale	(1,026,936,000)	(1,227,199,000)	(691,195,000)
Net cash provided by (used in) investing activities	95,284,000	(245,228,000)	199,381,000
Financing Activities: [Abstract]
Proceeds from issuance of common stock, net	0	0	109,296,000
Repurchase of preferred stock and warrant	0	0	(215,000,000)
Cash dividends paid on common stock	(59,485,000)	(59,302,000)	(53,295,000)
Cash dividends paid on preferred stock	0	0	(11,288,000)
Net cash used in financing activities	(227,792,000)	(13,525,000)	(416,109,000)
Increase (decrease) in cash and cash equivalents	41,081,000	(51,975,000)	(44,411,000)
Cash and cash equivalents at beginning of year	161,544,000	213,519,000	257,930,000
Cash and cash equivalents at end of year	202,625,000	161,544,000	213,519,000
Income taxes paid	37,604,000	53,628,000	60,456,000
Interest paid	44,060,000	59,858,000	93,402,000
Trustmark Corp (Parent Company Only) [Member]
Assets [Abstract]
Investment in banks	1,257,982,000	1,192,826,000
Other assets	20,071,000	19,411,000
Total Assets	1,278,053,000	1,212,237,000
Liabilities and Shareholders' Equity: [Abstract]
Accrued expense	1,160,000	897,000
Junior subordinated debt securities	61,856,000	61,856,000
Shareholders' equity	1,215,037,000	1,149,484,000
Total Liabilities and Shareholders' Equity	1,278,053,000	1,212,237,000
Revenue: [Abstract]
Dividends received from banks	61,138,000	61,843,000	64,807,000
Earnings of subsidiaries over distributions	46,818,000	40,036,000	29,606,000
Other income	54,000	68,000	95,000
Total Revenue	108,010,000	101,947,000	94,508,000
Expense: [Abstract]
Interest expense		0	0
Other expense	1,169,000	1,311,000	1,461,000
Total Expense	1,169,000	1,311,000	1,461,000
Net Income	106,841,000	100,636,000	93,047,000
Preferred stock dividends	0	0	10,124,000
Accretion of discount on preferred stock	0	0	9,874,000
Net Income Available to Common Shareholders	106,841,000	100,636,000	73,049,000
Operating Activities: [Abstract]
Net income	106,841,000	100,636,000	93,047,000
Adjustments to reconcile net income to net cash provided by operating activities:
Increase in investment in subsidiaries	(46,818,000)	(40,036,000)	(29,606,000)
Other	268,000	(252,000)	1,075,000
Net cash provided by operating activities	60,291,000	60,348,000	64,516,000
Investing Activities: [Abstract]
Payment for investments in subsidiaries	0	0	0
Repayment for investments in subsidiaries	0	248,000	115,000,000
Proceeds from maturities of securities available for sale	0	0	1,500,000
Purchases of securities available for sale	0	0	0
Net cash provided by (used in) investing activities	0	248,000	116,500,000
Financing Activities: [Abstract]
Repayments of line of credit	0	0	0
Repayments of advances from subsidiaries	0	(8,248,000)	0
Proceeds from issuance of common stock, net	0	0	109,296,000
Proceeds from issuance of preferred stock and warrant	0	0	0
Repurchase of preferred stock and warrant	0	0	(225,000,000)
Cash dividends paid on common stock	(59,485,000)	(59,302,000)	(53,295,000)
Cash dividends paid on preferred stock	0	0	(11,288,000)
Other common stock transactions, net	(141,000)	3,128,000	1,184,000
Other, net	0	(60,000)	0
Net cash used in financing activities	(59,626,000)	(64,482,000)	(179,103,000)
Increase (decrease) in cash and cash equivalents	665,000	(3,886,000)	1,913,000
Cash and cash equivalents at beginning of year	17,505,000	21,391,000	19,478,000
Cash and cash equivalents at end of year	18,170,000	17,505,000	21,391,000
Income taxes paid	37,600,000	53,600,000	60,500,000
Interest paid	$ 0	$ 0	$ 0