Other Real Estate and Covered Other Real Estate (Details) (USD $)	3 Months Ended																																3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013 Construction Land Development And Other Land Properties [Member]	Dec. 31, 2012 Construction Land Development And Other Land Properties [Member]	Mar. 31, 2013 1-4 Family Residential Properties [Member]	Dec. 31, 2012 1-4 Family Residential Properties [Member]	Mar. 31, 2013 Nonfarm, Nonresidential Properties [Member]	Dec. 31, 2012 Nonfarm, Nonresidential Properties [Member]	Mar. 31, 2013 Other Real Estate Properties [Member]	Dec. 31, 2012 Other Real Estate Properties [Member]	Mar. 31, 2013 Alabama [Member]	Dec. 31, 2012 Alabama [Member]	Mar. 31, 2013 Florida [Member]	Dec. 31, 2012 Florida [Member]	Mar. 31, 2013 Mississippi [Member]		Dec. 31, 2012 Mississippi [Member]		Mar. 31, 2013 Tennessee [Member]		Dec. 31, 2012 Tennessee [Member]		Mar. 31, 2013 Texas [Member]	Dec. 31, 2012 Texas [Member]	Mar. 31, 2013 Construction, Land Development And Other Land Properties [Member]	Dec. 31, 2012 Construction, Land Development And Other Land Properties [Member]	Mar. 31, 2013 1 - 4 Family Residential Properties [Member]	Dec. 31, 2012 1 - 4 Family Residential Properties [Member]	Mar. 31, 2013 Nonfarm, Nonresidential Properties [Member]	Dec. 31, 2012 Nonfarm, Nonresidential Properties [Member]	Mar. 31, 2013 Other Real Estate Properties [Member]	Dec. 31, 2012 Other Real Estate Properties [Member]	Mar. 31, 2013 BancTrust Financial Group, Inc. [Member]	Mar. 31, 2012 Bay Bank and Trust Company [Member]
Other real estate, excluding covered other real estate [Rollforward]
Balance at beginning of period	$ 78,189,000	$ 79,053,000									$ 28,870,000	$ 0	$ 30,662,000	$ 18,569,000	$ 26,457,000	[1]	$ 27,771,000	[1]	$ 18,339,000	[2]	$ 17,589,000	[2]	$ 14,078,000	$ 14,260,000	$ 65,664,000	$ 46,957,000	$ 12,396,000	$ 8,134,000	$ 37,746,000	$ 22,760,000	$ 2,600,000	$ 338,000
Additions	49,980,000	8,864,000
Disposals	(8,162,000)	(9,767,000)
Writedowns	(1,601,000)	(2,408,000)
Balance at end of period	118,406,000	75,742,000									28,870,000	0	30,662,000	18,569,000	26,457,000	[1]	27,771,000	[1]	18,339,000	[2]	17,589,000	[2]	14,078,000	14,260,000	65,664,000	46,957,000	12,396,000	8,134,000	37,746,000	22,760,000	2,600,000	338,000
(Loss) gain, net on the sale of noncovered other real estate included in ORE/Foreclosure expense	(15,000)	(416,000)
Business Acquisition [Line Items]
Other real estate acquired																																	41,200,000	2,600,000
Other real estate, excluding covered other real estate [Line Items]
Total other real estate, excluding covered other real estate	118,406,000	75,742,000									28,870,000	0	30,662,000	18,569,000	26,457,000	[1]	27,771,000	[1]	18,339,000	[2]	17,589,000	[2]	14,078,000	14,260,000	65,664,000	46,957,000	12,396,000	8,134,000	37,746,000	22,760,000	2,600,000	338,000
Other real estate, excluding covered other real estate by geographic location [Line Items]
Total other real estate, excluding covered other real estate	118,406,000	75,742,000									28,870,000	0	30,662,000	18,569,000	26,457,000	[1]	27,771,000	[1]	18,339,000	[2]	17,589,000	[2]	14,078,000	14,260,000	65,664,000	46,957,000	12,396,000	8,134,000	37,746,000	22,760,000	2,600,000	338,000
Covered other real estate, beginning of period	5,741,000	6,331,000	897,000	1,284,000	1,661,000	1,306,000	3,264,000	3,151,000	57,000	0
Transfers from covered loans	947,000	144,000
FASB ASC 310-30 adjustment for the residual recorded investment	(246,000)	(10,000)
Net transfers from covered loans	701,000	134,000
Disposals	(203,000)	(518,000)
Writedowns	(360,000)	(123,000)
Covered other real estate, end of period	5,879,000	5,824,000	897,000	1,284,000	1,661,000	1,306,000	3,264,000	3,151,000	57,000	0
(Loss) gain, net on the sale of covered other real estate included in ORE/Foreclosure expense	(59,000)	158,000
Schedule Of Covered Loans And Other Real Estate Acquired [Line Items]
Total covered other real estate	$ 5,879,000	$ 5,824,000	$ 897,000	$ 1,284,000	$ 1,661,000	$ 1,306,000	$ 3,264,000	$ 3,151,000	$ 57,000	$ 0

[1] Mississippi includes Central and Southern Mississippi Regions

[2] Tennessee includes Memphis, Tennessee and Northern Mississippi Regions