Non Purchased Loans - (Details 7) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Loan portfolio not subject to risk rating
Total	$ 6,235,805	$ 6,202,709
Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	741,466	717,490
Real estate – construction
Loan portfolio not subject to risk rating
Total	413,734	552,679
Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	1,917,567	1,878,177
Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	3,008,429	2,898,895
Installment loans to individuals
Loan portfolio not subject to risk rating
Total	154,609	155,468
Non purchased loans and leases
Loan portfolio not subject to risk rating
Total	4,834,085	4,713,572
Non purchased loans and leases | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	1,925,850	1,905,205
Non purchased loans and leases | Performing and Nonperforming | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	152,477	149,586
Non purchased loans and leases | Performing and Nonperforming | Lease financing
Loan portfolio not subject to risk rating
Total	47,816	46,841
Non purchased loans and leases | Performing and Nonperforming | Real estate – construction
Loan portfolio not subject to risk rating
Total	48,514	81,377
Non purchased loans and leases | Performing and Nonperforming | Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	1,270,768	1,225,345
Non purchased loans and leases | Performing and Nonperforming | Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	313,606	309,408
Non purchased loans and leases | Performing and Nonperforming | Installment loans to individuals
Loan portfolio not subject to risk rating
Total	92,669	92,648
Non purchased loans and leases | Performing
Loan portfolio not subject to risk rating
Total	1,920,688	1,900,508
Non purchased loans and leases | Performing | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	151,232	148,499
Non purchased loans and leases | Performing | Lease financing
Loan portfolio not subject to risk rating
Total	47,816	46,703
Non purchased loans and leases | Performing | Real estate – construction
Loan portfolio not subject to risk rating
Total	48,514	81,377
Non purchased loans and leases | Performing | Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	1,268,160	1,222,816
Non purchased loans and leases | Performing | Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	312,431	308,609
Non purchased loans and leases | Performing | Installment loans to individuals
Loan portfolio not subject to risk rating
Total	92,535	92,504
Non purchased loans and leases | Non- Performing
Loan portfolio not subject to risk rating
Total	5,162	4,697
Non purchased loans and leases | Non- Performing | Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	1,245	1,087
Non purchased loans and leases | Non- Performing | Lease financing
Loan portfolio not subject to risk rating
Total	0	138
Non purchased loans and leases | Non- Performing | Real estate – construction
Loan portfolio not subject to risk rating
Total	0	0
Non purchased loans and leases | Non- Performing | Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	2,608	2,529
Non purchased loans and leases | Non- Performing | Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	1,175	799
Non purchased loans and leases | Non- Performing | Installment loans to individuals
Loan portfolio not subject to risk rating
Total	$ 134	$ 144