Business Combinations (Details) (USD $)	3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 BancTrust Financial Group, Inc. [Member]	Mar. 31, 2012 BancTrust Financial Group, Inc. [Member]	Jun. 30, 2012 Bay Bank and Trust Company [Member]	Mar. 31, 2012 Bay Bank and Trust Company [Member]	Sep. 30, 2012 Bay Bank and Trust Company [Member]	Mar. 16, 2012 Bay Bank and Trust Company [Member]	Sep. 30, 2011 Heritage Banking Group Business Acquisition [Member]	Apr. 15, 2011 Heritage Banking Group Business Acquisition [Member]
Business Acquisition [Line Items]
Proposed business acquisition, number of offices to be acquired					49
Proposed business acquisition, loans to be acquired						$ 1,300,000,000
Age of acquired entity (in years)										76		90
FDIC loss-share transaction asset coverage agreement		151,900,000		151,900,000
FDIC loss-share agreement covered loan and other real estate losses (in hundredths)		80.00%		80.00%
FDIC loss-share agreement term for single family residential mortgage loans and foreclosed real estate		10 years		10 years
FDIC loss-share agreement term for commercial loans and related foreclosures		5 years		5 years
FDIC loss-share agreement reimbursement term for recoveries of covered losses		3 years		3 years
Assets [Abstract]
Cash and due from banks										88,154,000		50,447,000
Federal funds sold												1,000,000
Securities available for sale										26,369,000		6,389,000
Acquired noncovered loans										97,914,000		9,644,000
Acquired covered loans												97,770,000
Premises and equipment, net										9,466,000		55,000
Identifiable intangible assets										7,017,000		902,000
Other real estate										2,569,000
Covered other real estate												7,485,000
FDIC indemnification asset												33,333,000
Other assets										3,471,000		218,000
Proposed Business Acquisition Equity to be Issued Per Share Of Acquired Company (in dollars per share)					0.125
Proposed Business combination price per share of stock issued (in dollars per share)					$ 24.66
Proposed Business Acquisition Share Price (per share)					3.08
Preferred stock and warrants to be repurchased					50,000,000
Total assets acquired	234,960,000	207,243,000	234,960,000	207,243,000						234,960,000		207,243,000
Liabilities [Abstract]
Deposits						1,800,000,000				208,796,000		204,349,000
Short-term borrowings												23,157,000
Other liabilities										526,000		730,000
Total Liabilities										209,322,000		228,236,000
Net assets acquired at fair value										25,638,000		(20,993,000)
Consideration paid to acquiree									22,003,000
Proposed business acquisition, cost of acquired entity					55,400,000
Cash received on acquisition											28,449,000
Bargain purchase gain			3,635,000	7,456,000			881,000	2,800,000	3,635,000		7,456,000
Income taxes									0		2,852,000
Bargain purchase gain, net of taxes									3,635,000		4,604,000
Business acquisition, cost of acquired entity, cash paid										10,000,000
Proposed business acquisition, equity to be issued (in shares)					2,245,923
Business acquisition, equity issued (in shares)									510,000
Business acquisition, equity issued, value assigned										12,000,000
Business acquisition, total transaction expenses								2,600,000
Business acquisition, severance expense								672,000
Business acquisition, contract termination and other expenses								1,900,000
Revenue from the operations of Bay Bank included in TNB's operations results									10,000,000
Net income available to common shareholders	$ 29,904,000	$ 26,968,000	$ 89,573,000	$ 82,583,000					$ 1,200,000