Purchased Loans (Details 1) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Past due and nonaccrual loans
Total loans, gross	$ 6,205,118	$ 5,414,625
Unearned income	(2,409)	(1,163)
Loans, net of unearned income	6,202,709	5,413,462
Commercial, financial, agricultural
Past due and nonaccrual loans
Total loans, gross	717,490	636,837
Loans, net of unearned income	717,490	636,837
Lease financing
Past due and nonaccrual loans
Total loans, gross	49,250	35,978
Real estate – construction
Past due and nonaccrual loans
Total loans, gross	552,679	357,665
Loans, net of unearned income	552,679	357,665
Real estate – 1-4 family mortgage
Past due and nonaccrual loans
Total loans, gross	1,878,177	1,735,323
Loans, net of unearned income	1,878,177	1,735,323
Real estate – commercial mortgage
Past due and nonaccrual loans
Total loans, gross	2,898,895	2,533,729
Loans, net of unearned income	2,898,895	2,533,729
Installment loans to individuals
Past due and nonaccrual loans
Total loans, gross	108,627	115,093
Loans, net of unearned income	155,468	149,908
Purchased
Past due and nonaccrual loans
Total loans, gross	1,489,137	1,583,028
Unearned income	0	0
Loans, net of unearned income	1,489,137	1,583,028
Purchased | Accruing Loans
Past due and nonaccrual loans
Current Loans	1,457,912	1,544,164
Unearned income	0	0
Loans, net of unearned income	1,477,790	1,567,638
Purchased | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	9,063	8,407
Purchased | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	10,815	15,067
Purchased | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	5,280	12,713
Unearned income	0	0
Loans, net of unearned income	11,347	15,390
Purchased | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	677	158
Purchased | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	5,390	2,519
Purchased | Commercial, financial, agricultural
Past due and nonaccrual loans
Total loans, gross	128,200	151,430
Loans, net of unearned income	128,200	151,430
Purchased | Commercial, financial, agricultural | Accruing Loans
Past due and nonaccrual loans
Current Loans	125,417	148,942
Total loans, gross	127,230	151,101
Purchased | Commercial, financial, agricultural | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	823	1,120
Purchased | Commercial, financial, agricultural | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	990	1,039
Purchased | Commercial, financial, agricultural | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	329	264
Total loans, gross	970	329
Purchased | Commercial, financial, agricultural | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	260	0
Purchased | Commercial, financial, agricultural | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	381	65
Purchased | Lease financing
Past due and nonaccrual loans
Total loans, gross	0	0
Purchased | Lease financing | Accruing Loans
Past due and nonaccrual loans
Current Loans	0	0
Total loans, gross	0	0
Purchased | Lease financing | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Lease financing | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Lease financing | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	0	0
Total loans, gross	0	0
Purchased | Lease financing | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Lease financing | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Real estate – construction
Past due and nonaccrual loans
Total loans, gross	68,753	65,964
Loans, net of unearned income	68,753	65,964
Purchased | Real estate – construction | Accruing Loans
Past due and nonaccrual loans
Current Loans	67,760	65,788
Total loans, gross	68,608	65,964
Purchased | Real estate – construction | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	527	0
Purchased | Real estate – construction | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	321	176
Purchased | Real estate – construction | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	0	0
Total loans, gross	145	0
Purchased | Real estate – construction | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Real estate – construction | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	145	0
Purchased | Real estate – 1-4 family mortgage
Past due and nonaccrual loans
Total loans, gross	452,447	531,095
Loans, net of unearned income	452,447	531,095
Purchased | Real estate – 1-4 family mortgage | Accruing Loans
Past due and nonaccrual loans
Current Loans	440,258	514,912
Total loans, gross	448,212	525,297
Purchased | Real estate – 1-4 family mortgage | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	4,572	4,735
Purchased | Real estate – 1-4 family mortgage | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	3,382	5,650
Purchased | Real estate – 1-4 family mortgage | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	1,771	3,834
Total loans, gross	4,235	5,798
Purchased | Real estate – 1-4 family mortgage | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	417	158
Purchased | Real estate – 1-4 family mortgage | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	2,047	1,806
Purchased | Real estate – commercial mortgage
Past due and nonaccrual loans
Total loans, gross	823,758	804,680
Loans, net of unearned income	823,758	804,680
Purchased | Real estate – commercial mortgage | Accruing Loans
Past due and nonaccrual loans
Current Loans	808,886	784,863
Total loans, gross	818,043	795,477
Purchased | Real estate – commercial mortgage | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	3,045	2,458
Purchased | Real estate – commercial mortgage | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	6,112	8,156
Purchased | Real estate – commercial mortgage | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	3,054	8,608
Total loans, gross	5,715	9,203
Purchased | Real estate – commercial mortgage | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Real estate – commercial mortgage | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	2,661	595
Purchased | Installment loans to individuals
Past due and nonaccrual loans
Total loans, gross	15,979	29,859
Loans, net of unearned income	15,979	29,859
Purchased | Installment loans to individuals | Accruing Loans
Past due and nonaccrual loans
Current Loans	15,591	29,659
Total loans, gross	15,697	29,799
Purchased | Installment loans to individuals | Accruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	96	94
Purchased | Installment loans to individuals | Accruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	10	46
Purchased | Installment loans to individuals | Nonaccruing Loans
Past due and nonaccrual loans
Current Loans	126	7
Total loans, gross	282	60
Purchased | Installment loans to individuals | Nonaccruing Loans | 30-89 Days Past Due
Past due and nonaccrual loans
Loans past due	0	0
Purchased | Installment loans to individuals | Nonaccruing Loans | 90 Days or More Past Due
Past due and nonaccrual loans
Loans past due	$ 156	$ 53