Business Combinations, BancTrust Financial Group (Details) (USD $)	0 Months Ended	6 Months Ended		12 Months Ended
	Feb. 15, 2013	Jun. 30, 2014 Market	Jun. 30, 2013	Dec. 31, 2013
Business Acquisition [Line Items]
Decrease in acquired non covered loans as measurement period adjustment				$ 6,800,000
Assets [Abstract]
Total Assets		0	1,849,929,000
Liabilities [Abstract]
Total Liabilities		0	1,821,066,000
Goodwill		365,500,000		372,851,000
BancTrust Financial Group, Inc. [Member]
Business Acquisition [Line Items]
Age of acquired entity	26 years
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
Decrease in acquired non covered loans as measurement period adjustment				6,800,000
Decrease in Premises and equipment as measurement period adjustment				627,000
Decrease in other real estate as measurement period adjustment				2,600,000
Increase in deferred tax asset as measurement period adjustment				3,400,000
Increase in goodwill as measurement period adjustment				6,300,000
Transfer to other real estate as measurement period adjustment				1,600,000
Decrease in goodwill with a corresponding increase in the deferred tax asset as a measurement period adjustment		7,400,000
Assets [Abstract]
Cash and due from banks	141,616,000
Securities available for sale	528,016,000
Loans held for sale	1,050,000
Acquired noncovered loans	944,235,000
Premises and equipment, net	54,952,000
Identifiable intangible assets	33,498,000
Other real estate	40,103,000
Other assets	109,423,000
Total Assets	1,852,893,000
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	31,827,000
Goodwill	74,247,000
Net assets acquired at fair value	106,074,000
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		10 years
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