Purchased Loans - Loans Acquired with Deteriorated Credit Quality (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	$ 9,038,458	$ 9,034,103
Purchased loans | Receivables Acquired with Deteriorated Credit Quality
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	208,846	222,254
Purchased loans | Receivables Acquired with Deteriorated Credit Quality | Commercial, financial, agricultural
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	24,847	29,143
Purchased loans | Receivables Acquired with Deteriorated Credit Quality | Real estate – 1-4 family mortgage
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	43,824	48,243
Purchased loans | Receivables Acquired with Deteriorated Credit Quality | Real estate – commercial mortgage
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	136,282	140,438
Purchased loans | Receivables Acquired with Deteriorated Credit Quality | Installment loans to individuals
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	$ 3,893	$ 4,430