Acquired Loans Part 4 (Details) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2014 CreditRiskGrade	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Feb. 15, 2013
Allowance for loan loss [Abstract]
Balance, beginning	$ 9,636,000	$ 6,075,000	$ 502,000
Provision for loan losses, acquired loans	6,171,000	6,039,000	5,528,000
Loans charged-off	(6,147,000)	(4,094,000)	(371,000)
Recoveries	2,399,000	1,616,000	416,000
Net (charge-offs) recoveries	(3,748,000)	(2,478,000)	45,000
Balance, ending	12,059,000	9,636,000	6,075,000	9,636,000
Number of individual credit risk grades	10
Nonaccrual loans not accounted for under FASB ASC Topic 310-30	1,100,000	2,400,000		2,400,000
BancTrust Financial Group, Inc. [Member]
Allowance for loan loss [Abstract]
Revolving credit agreements acquired					153,900,000
Decrease in acquired non covered loans as measurement period adjustment		6,800,000		6,800,000
Covered Loans [Member]
Allowance for loan loss [Abstract]
Balance, beginning	2,387,000	4,190,000	502,000
Provision for loan losses, acquired loans	(978,000)	(1,328,000)	3,612,000
Loans charged-off	127,000	(460,000)	(81,000)
Recoveries	(18,000)	(15,000)	157,000
Net (charge-offs) recoveries	109,000	(475,000)	76,000
Balance, ending	1,518,000	2,387,000	4,190,000	2,387,000
Noncovered Loans [Member]
Allowance for loan loss [Abstract]
Balance, beginning	7,249,000	1,885,000	0
Provision for loan losses, acquired loans	7,149,000	7,367,000	1,916,000
Loans charged-off	(6,274,000)	(3,634,000)	(290,000)
Recoveries	2,417,000	1,631,000	259,000
Net (charge-offs) recoveries	(3,857,000)	(2,003,000)	(31,000)
Balance, ending	$ 10,541,000	$ 7,249,000	$ 1,885,000	$ 7,249,000