Purchased Loans - Loans Acquired with Deteriorated Credit Quality (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	$ 9,004,595	$ 9,034,103
Purchased loans | Receivables Acquired with Deteriorated Credit Quality
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	191,345	222,254
Purchased loans | Receivables Acquired with Deteriorated Credit Quality | Commercial, financial, agricultural
Loans acquired with deteriorated credit quality
Total Purchased Credit Deteriorated Loans	23,626	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	42,679	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	121,698	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	$ 3,342	$ 4,430