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		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
BancTrust Financial Group, Inc. [Member]
Unaudited pro forma financial information [Abstract]
Net Interest Income	$ 99,228	$ 103,322	$ 195,742	$ 206,194
Total Noninterest Income	43,714	46,769	89,916	94,403
Net income	$ 31,121	$ 35,401	$ 63,796	$ 69,932
Pro Forma Earnings Per Common Share [Abstract]
Basic (in dollars per share)	$ 0.46	$ 0.53	$ 0.95	$ 1.05
Diluted (in dollars per share)	$ 0.46	$ 0.53	$ 0.95	$ 1.05