Purchased Loans (Details 6) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Loan portfolio not subject to risk rating
Total	$ 6,371,007	$ 6,202,709
Commercial, financial, agricultural
Loan portfolio not subject to risk rating
Total	760,582	717,490
Real estate – construction
Loan portfolio not subject to risk rating
Total	460,807	552,679
Real estate – 1-4 family mortgage
Loan portfolio not subject to risk rating
Total	1,952,394	1,878,177
Real estate – commercial mortgage
Loan portfolio not subject to risk rating
Total	3,040,963	2,898,895
Installment loans to individuals
Loan portfolio not subject to risk rating
Total	156,261	155,468
Purchased loans
Loan portfolio not subject to risk rating
Total	1,312,109	1,489,137
Purchased loans | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	292,283	316,127
Purchased loans | Performing
Loan portfolio not subject to risk rating
Total	289,927	313,852
Purchased loans | Non-Performing
Loan portfolio not subject to risk rating
Total	2,356	2,275
Purchased loans | Commercial, financial, agricultural | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	11,895	9,568
Purchased loans | Commercial, financial, agricultural | Performing
Loan portfolio not subject to risk rating
Total	11,833	9,489
Purchased loans | Commercial, financial, agricultural | Non-Performing
Loan portfolio not subject to risk rating
Total	62	79
Purchased loans | Real estate – construction | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	939	4,067
Purchased loans | Real estate – construction | Performing
Loan portfolio not subject to risk rating
Total	939	3,601
Purchased loans | Real estate – construction | Non-Performing
Loan portfolio not subject to risk rating
Total	0	466
Purchased loans | Real estate – 1-4 family mortgage | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	241,950	267,201
Purchased loans | Real estate – 1-4 family mortgage | Performing
Loan portfolio not subject to risk rating
Total	240,610	265,697
Purchased loans | Real estate – 1-4 family mortgage | Non-Performing
Loan portfolio not subject to risk rating
Total	1,340	1,504
Purchased loans | Real estate – commercial mortgage | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	26,195	21,411
Purchased loans | Real estate – commercial mortgage | Performing
Loan portfolio not subject to risk rating
Total	25,403	21,353
Purchased loans | Real estate – commercial mortgage | Non-Performing
Loan portfolio not subject to risk rating
Total	792	58
Purchased loans | Installment loans to individuals | Performing and Nonperforming
Loan portfolio not subject to risk rating
Total	11,304	13,880
Purchased loans | Installment loans to individuals | Performing
Loan portfolio not subject to risk rating
Total	11,142	13,712
Purchased loans | Installment loans to individuals | Non-Performing
Loan portfolio not subject to risk rating
Total	$ 162	$ 168