Parent Company Only Financial Information (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Assets [Abstract]
Other assets	$ 568,685,000	$ 582,363,000
Total Assets	12,250,633,000	11,790,383,000
Liabilities and Shareholders' Equity [Abstract]
Junior subordinated debt securities	61,856,000	61,856,000
Shareholders' equity	1,419,940,000	1,354,953,000	1,287,369,000	1,215,037,000
Total Liabilities and Shareholders' Equity	12,250,633,000	11,790,383,000
Expense [Abstract]
Net Income	123,562,000	117,060,000	117,283,000
Operating Activities [Abstract]
Net income	123,562,000	117,060,000	117,283,000
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Other	16,337,000	7,523,000	22,497,000
Net cash provided by operating activities	211,267,000	301,183,000	112,277,000
Investing Activities: [Abstract]
Net cash (used in) provided by investing activities	(556,255,000)	(258,967,000)	173,739,000
Financing Activities [Abstract]
Cash dividends paid on common stock	(62,474,000)	(62,276,000)	(59,961,000)
Net cash provided by (used in) financing activities	315,200,000	72,056,000	(257,152,000)
(Decrease) Increase in cash and cash equivalents	(29,788,000)	114,272,000	28,864,000
Cash and cash equivalents at beginning of year	345,761,000	231,489,000	202,625,000
Cash and cash equivalents at end of year	315,973,000	345,761,000	231,489,000
Income taxes paid	13,710,000	14,520,000	57,834,000
Interest paid	22,268,000	25,715,000	31,496,000
Trustmark Corp (Parent Company Only) [Member]
Assets [Abstract]
Investment in banks	1,463,676,000	1,394,250,000
Other assets	18,663,000	25,314,000
Total Assets	1,482,339,000	1,419,564,000
Liabilities and Shareholders' Equity [Abstract]
Accrued expense	543,000	2,755,000
Junior subordinated debt securities	61,856,000	61,856,000
Shareholders' equity	1,419,940,000	1,354,953,000
Total Liabilities and Shareholders' Equity	1,482,339,000	1,419,564,000
Revenue [Abstract]
Dividends received from banks	64,351,000	64,155,000	72,216,000
Earnings of subsidiaries over distributions	60,783,000	54,195,000	46,220,000
Other income	55,000	64,000	59,000
Total Revenue	125,189,000	118,414,000	118,495,000
Expense [Abstract]
Other expense	1,627,000	1,354,000	1,212,000
Total Expense	1,627,000	1,354,000	1,212,000
Net Income	123,562,000	117,060,000	117,283,000
Operating Activities [Abstract]
Net income	123,562,000	117,060,000	117,283,000
Adjustments to reconcile net income to net cash provided by operating activities [Abstract]
Increase in investment in subsidiaries	(60,783,000)	(54,195,000)	(46,220,000)
Other	(2,158,000)	962,000	(376,000)
Net cash provided by operating activities	60,621,000	63,827,000	70,687,000
Investing Activities: [Abstract]
Payment for investments in subsidiaries	0	(73,263,000)	(10,003,000)
Repayment for investments in subsidiaries	0	106,000,000	0
Net cash (used in) provided by investing activities	0	32,737,000	(10,003,000)
Financing Activities [Abstract]
Repayments of advances from subsidiaries	0	(33,000,000)	0
Cash dividends paid on common stock	(62,474,000)	(62,276,000)	(59,961,000)
Other common stock transactions, net	(1,502,000)	2,832,000	(1,237,000)
Net cash provided by (used in) financing activities	(63,976,000)	(92,444,000)	(61,198,000)
(Decrease) Increase in cash and cash equivalents	(3,355,000)	4,120,000	(514,000)
Cash and cash equivalents at beginning of year	21,776,000	17,656,000	18,170,000
Cash and cash equivalents at end of year	18,421,000	21,776,000	17,656,000
Income taxes paid	13,700,000	14,500,000	57,800,000
Interest paid	$ 0	$ 0	$ 0