Purchased Loans - Purchased With Deteriorated Credit (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	$ 7,574,111	$ 6,159,972
Purchased | Receivables Acquired with Deteriorated Credit Quality
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	227,260	271,758
Purchased | Receivables Acquired with Deteriorated Credit Quality | Commercial, financial, agricultural
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	15,315	11,994
Purchased | Receivables Acquired with Deteriorated Credit Quality | Lease financing
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	0	0
Purchased | Receivables Acquired with Deteriorated Credit Quality | Real estate – construction
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	0	840
Purchased | Receivables Acquired with Deteriorated Credit Quality | Real estate – 1-4 family mortgage
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	53,969	71,952
Purchased | Receivables Acquired with Deteriorated Credit Quality | Real estate – commercial mortgage
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	156,338	184,987
Purchased | Receivables Acquired with Deteriorated Credit Quality | Installment loans to individuals
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	$ 1,638	$ 1,985