Business Combinations (Details) (USD $)	12 Months Ended					12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Trustmark National Bank [Member] Heritage Banking Group Business Acquisition [Member]	Apr. 15, 2011 Trustmark National Bank [Member] Heritage Banking Group Business Acquisition [Member]	Dec. 31, 2011 Trustmark National Bank [Member] Bay Bank and Trust Company Business Acquisition [Member]
Assets [Abstract]
Cash and due from banks					$ 50,447,000
Federal funds sold					1,000,000
Securities available for sale					6,389,000
LHFI, excluding covered loans					9,644,000
Covered loans					97,770,000
Premises and equipment, net					55,000
Identifiable intangible assets					902,000
Covered other real estate					7,485,000
FDIC indemnification asset					33,333,000
Other assets					218,000
Total Assets	207,243,000	0	0		207,243,000
Liabilities [Abstract]
Deposits					204,349,000
Short-term borrowings					23,157,000
Other liabilities					730,000
Total Liabilities	228,236,000	0	0		228,236,000
Net assets acquired at fair value					(20,993,000)
Cash received on acquisition	78,896,000	0	0	28,449,000
Bargain purchase gain	7,456,000	0	0	7,456,000
Income taxes				2,852,000
Bargain purchase gain, net of taxes				4,604,000
Age of acquired entity (in years)				90Y		76Y
FDIC loss-share transaction asset coverage agreement				151,900,000
FDIC loss-share agreement covered loan and other real estate losses (in hundredths)				80.00%
FDIC loss-share agreement term for single family residential mortgage loans and foreclosed real estate (in years)				10Y
FDIC loss-share agreement term for commercial loans and related foreclosures (in years)				5Y
FDIC loss-share agreement reimbursement term for recoveries of covered losses (in years)				3Y
Bargain purchase transaction	7,456,000	0	0	7,456,000
Added revenue in period from acquisition				13,000,000
Added net income available to common shareholders in the period from acquisition				6,500,000
Loans receivable of acquisition						116,900,000
Deposits payable of acquisition						206,600,000
Business acquisition purchase price						22,000,000
Business acquisition, cash paid						10,000,000
Business acquisition, equity issued						$ 12,000,000
Business acquisition, tangible book value acquired (in hundredths)						86.00%