Non Purchased Loans - Performing Status (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 9,689,638	$ 9,083,129
Commercial, financial, agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,367,972	1,295,912
Real estate – construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	826,483	740,668
Real estate – 1-4 family mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,866,613	2,795,343
Real estate – commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	4,244,265	4,051,509
Installment loans to individuals
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	384,305	199,697
Non-Purchased
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	7,587,974	6,389,712
Non-Purchased | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,933,132	2,560,335
Non-Purchased | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,918,059	2,551,833
Non-Purchased | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	15,073	8,502
Non-Purchased | Commercial, financial, agricultural | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	248,891	234,547
Non-Purchased | Commercial, financial, agricultural | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	247,575	233,046
Non-Purchased | Commercial, financial, agricultural | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,316	1,501
Non-Purchased | Lease financing | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	81,875	61,865
Non-Purchased | Lease financing | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	81,649	61,776
Non-Purchased | Lease financing | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	226	89
Non-Purchased | Real estate – construction | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	66,241	66,551
Non-Purchased | Real estate – construction | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	66,241	66,551
Non-Purchased | Real estate – construction | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Non-Purchased | Real estate – 1-4 family mortgage | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,003,619	1,757,406
Non-Purchased | Real estate – 1-4 family mortgage | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,992,331	1,751,994
Non-Purchased | Real estate – 1-4 family mortgage | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	11,288	5,412
Non-Purchased | Real estate – commercial mortgage | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	332,669	339,542
Non-Purchased | Real estate – commercial mortgage | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	330,714	338,367
Non-Purchased | Real estate – commercial mortgage | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,955	1,175
Non-Purchased | Installment loans to individuals | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	199,837	100,424
Non-Purchased | Installment loans to individuals | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	199,549	100,099
Non-Purchased | Installment loans to individuals | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 288	$ 325