Non Purchased Loans (Details 6) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Loan portfolio not subject to risk rating
Total	$ 6,202,709	$ 5,413,462
Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	717,490	636,837
Real estate – construction
Loan portfolio not subject to risk rating
Total	552,679	357,665
Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	1,878,177	1,735,323
Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	2,898,895	2,533,729
Installment loans to individuals
Loan portfolio not subject to risk rating
Total	155,468	149,908
Non-Purchased
Loan portfolio not subject to risk rating
Total	4,713,572	3,830,434
Non-Purchased | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	1,905,205	1,657,516
Non-Purchased | Performing
Loan portfolio not subject to risk rating
Total	1,900,508	1,654,075
Non-Purchased | Non-Performing
Loan portfolio not subject to risk rating
Total	4,697	3,441
Non-Purchased | Commercial, financial, agricultural | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	149,586	139,988
Non-Purchased | Commercial, financial, agricultural | Performing
Loan portfolio not subject to risk rating
Total	148,499	139,895
Non-Purchased | Commercial, financial, agricultural | Non-Performing
Loan portfolio not subject to risk rating
Total	1,087	93
Non-Purchased | Lease financing | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	46,841	34,815
Non-Purchased | Lease financing | Performing
Loan portfolio not subject to risk rating
Total	46,703	34,815
Non-Purchased | Lease financing | Non-Performing
Loan portfolio not subject to risk rating
Total	138	0
Non-Purchased | Real estate – construction | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	81,377	67,256
Non-Purchased | Real estate – construction | Performing
Loan portfolio not subject to risk rating
Total	81,377	67,256
Non-Purchased | Real estate – construction | Non-Performing
Loan portfolio not subject to risk rating
Total	0	0
Non-Purchased | Real estate – 1-4 family mortgage | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	1,225,345	1,048,525
Non-Purchased | Real estate – 1-4 family mortgage | Performing
Loan portfolio not subject to risk rating
Total	1,222,816	1,046,100
Non-Purchased | Real estate – 1-4 family mortgage | Non-Performing
Loan portfolio not subject to risk rating
Total	2,529	2,425
Non-Purchased | Real estate – commercial mortgage | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	309,408	281,755
Non-Purchased | Real estate – commercial mortgage | Performing
Loan portfolio not subject to risk rating
Total	308,609	280,888
Non-Purchased | Real estate – commercial mortgage | Non-Performing
Loan portfolio not subject to risk rating
Total	799	867
Non-Purchased | Installment loans to individuals | Performing and Non-Performing
Loan portfolio not subject to risk rating
Total	92,648	85,177
Non-Purchased | Installment loans to individuals | Performing
Loan portfolio not subject to risk rating
Total	92,504	85,121
Non-Purchased | Installment loans to individuals | Non-Performing
Loan portfolio not subject to risk rating
Total	$ 144	$ 56