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
Purchased
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	2,101,664	2,693,417
Purchased | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	543,747	619,073
Purchased | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	539,747	614,814
Purchased | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	4,000	4,259
Purchased | Commercial, financial, agricultural | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	13,935	21,372
Purchased | Commercial, financial, agricultural | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	13,935	21,303
Purchased | Commercial, financial, agricultural | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	69
Purchased | Lease financing | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Purchased | Lease financing | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Purchased | Lease financing | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Purchased | Real estate – construction | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,725	3,185
Purchased | Real estate – construction | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	1,725	3,185
Purchased | Real estate – construction | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	0	0
Purchased | Real estate – 1-4 family mortgage | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	398,114	530,404
Purchased | Real estate – 1-4 family mortgage | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	394,476	526,699
Purchased | Real estate – 1-4 family mortgage | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	3,638	3,705
Purchased | Real estate – commercial mortgage | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	30,573	31,136
Purchased | Real estate – commercial mortgage | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	30,472	30,951
Purchased | Real estate – commercial mortgage | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	101	185
Purchased | Installment loans to individuals | Performing and Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	99,400	32,976
Purchased | Installment loans to individuals | Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	99,139	32,676
Purchased | Installment loans to individuals | Non-Performing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 261	$ 300