Business Combinations, BancTrust Financial Group (Details) (USD $)	3 Months Ended		0 Months Ended	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Feb. 15, 2013 BancTrust Financial Group, Inc. [Member]	Mar. 31, 2013 BancTrust Financial Group, Inc. [Member] Market
Business Acquisition [Line Items]
Age of acquired entity (in years)			26
Preferred stock and warrants repurchased			$ 50,000,000
Issued value of preferred stock associated warrant under capital purchase program			52,600,000
Equity issued, per share of acquired company (in shares)			0.125
Assets [Abstract]
Cash and due from banks			141,616,000
Securities			528,016,000
Loans held for sale			1,050,000
Acquired noncovered loans			951,011,000
Premises and equipment, net			57,146,000
Identifiable intangible assets			33,498,000
Other real estate			41,168,000
Other assets			98,373,000
Total Assets			1,851,878,000
Liabilities [Abstract]
Deposits			1,740,254,000
Other borrowings			64,051,000
Other liabilities			16,761,000
Total Liabilities			1,821,066,000
Net identified assets acquired at fair value			30,812,000
Goodwill			75,262,000
Net assets acquired at fair value			106,074,000
Consideration paid to acquiree				75,300,000
Net income available to common shareholders	24,866,000	30,320,000		2,000,000
Equity issued (in shares)			2,240,000
Business acquisition, equity issued, value assigned			53,500,000
Business acquisition, closing stock price (in dollars per share)			$ 23.83
Number of markets entered due to acquisition				15
Amortization period of acquired intangible asset (in years)				10
Revenue from the operations of Bay Bank included in TNB's operations results				9,400,000
Business acquisition, total transaction expenses				9,400,000
Business acquisition, severance expense				1,400,000
Business acquisition, contract termination and other expenses				$ 7,900,000