Business Combinations, BancTrust Financial Group, Pro forma Financial Information (Details) (BancTrust Financial Group, Inc. [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
BancTrust Financial Group, Inc. [Member]
Unaudited pro forma financial information [Abstract]
Net Interest Income	$ 98,429	$ 103,287	$ 294,171	$ 309,481
Total Noninterest Income	47,133	48,110	137,049	142,513
Net income	$ 33,034	$ 34,818	$ 96,830	$ 104,750
Pro Forma Earnings Per Common Share [Abstract]
Basic (in dollars per share)	$ 0.49	$ 0.52	$ 1.40	$ 1.57
Diluted (in dollars per share)	$ 0.49	$ 0.52	$ 1.40	$ 1.56