Non Purchased Loans - Restructured Loans by Class (Details) - Non-Purchased $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) loan	Dec. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan
Restructured loans
Number of Loans (loans) | loan	14	12	25
Pre-Modification Outstanding Recorded Investment	$ 1,616	$ 1,698	$ 2,753
Post-Modification Outstanding Recorded Investment	$ 1,232	$ 1,685	$ 2,434
Commercial, financial, agricultural
Restructured loans
Number of Loans (loans) | loan	2	0	0
Pre-Modification Outstanding Recorded Investment	$ 331	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 330	$ 0	$ 0
Lease financing
Restructured loans
Number of Loans (loans) | loan	0	0	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 0	$ 0
Post-Modification Outstanding Recorded Investment	$ 0	$ 0	$ 0
Real estate – construction
Restructured loans
Number of Loans (loans) | loan	0	1	0
Pre-Modification Outstanding Recorded Investment	$ 0	$ 510	$ 0
Post-Modification Outstanding Recorded Investment	$ 0	$ 518	$ 0
Real estate – 1-4 family mortgage
Restructured loans
Number of Loans (loans) | loan	8	11	22
Pre-Modification Outstanding Recorded Investment	$ 598	$ 1,188	$ 2,202
Post-Modification Outstanding Recorded Investment	$ 586	$ 1,167	$ 2,035
Real estate – commercial mortgage
Restructured loans
Number of Loans (loans) | loan	3	0	2
Pre-Modification Outstanding Recorded Investment	$ 683	$ 0	$ 484
Post-Modification Outstanding Recorded Investment	$ 313	$ 0	$ 332
Installment loans to individuals
Restructured loans
Number of Loans (loans) | loan	1	0	1
Pre-Modification Outstanding Recorded Investment	$ 4	$ 0	$ 67
Post-Modification Outstanding Recorded Investment	$ 3	$ 0	$ 67