Credit Quality of Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	$ 47,034	$ 37,396
Current	1,090,221	1,146,030
Total Loans	1,137,255	1,183,426
Recorded Investment, 90 days past due and Accruing	1	728
Commercial, financial and agricultural
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	18,207	17,935
Current	382,841	417,272
Total Loans	401,048	435,207
Recorded Investment, 90 days past due and Accruing	1	545
Real estate - construction
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	2,298	806
Current	92,381	89,481
Total Loans	94,679	90,287
Recorded Investment, 90 days past due and Accruing	0	125
Real estate – commercial
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	23,090	16,454
Current	415,689	431,952
Total Loans	438,779	448,406
Recorded Investment, 90 days past due and Accruing	0	58
Real estate - residential
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	2,981	1,859
Current	142,690	144,892
Total Loans	145,671	146,751
Recorded Investment, 90 days past due and Accruing	0	0
Installment loans to individuals
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	377	342
Current	50,511	56,056
Total Loans	50,888	56,398
Recorded Investment, 90 days past due and Accruing	0	0
Lease financing receivable
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	0	0
Current	692	732
Total Loans	692	732
Recorded Investment, 90 days past due and Accruing	0	0
Other loans
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	81	0
Current	5,417	5,645
Total Loans	5,498	5,645
Recorded Investment, 90 days past due and Accruing	0	0
Financing Receivables, 30 to 59 Days Past Due [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	9,767	9,041
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial, financial and agricultural
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	2,235	1,195
Financing Receivables, 30 to 59 Days Past Due [Member] | Real estate - construction
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	927	616
Financing Receivables, 30 to 59 Days Past Due [Member] | Real estate – commercial
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	5,681	5,889
Financing Receivables, 30 to 59 Days Past Due [Member] | Real estate - residential
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	657	1,065
Financing Receivables, 30 to 59 Days Past Due [Member] | Installment loans to individuals
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	202	276
Financing Receivables, 30 to 59 Days Past Due [Member] | Lease financing receivable
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Other loans
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	65	0
Financing Receivables, 60 to 89 Days Past Due [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	11,692	8,562
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial, financial and agricultural
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	3,156	1,893
Financing Receivables, 60 to 89 Days Past Due [Member] | Real estate - construction
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	1,179	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Real estate – commercial
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	6,079	6,402
Financing Receivables, 60 to 89 Days Past Due [Member] | Real estate - residential
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	1,137	235
Financing Receivables, 60 to 89 Days Past Due [Member] | Installment loans to individuals
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	125	32
Financing Receivables, 60 to 89 Days Past Due [Member] | Lease financing receivable
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Other loans
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	16	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	25,575	19,793
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial, financial and agricultural
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	12,816	14,847
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real estate - construction
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	192	190
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real estate – commercial
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	11,330	4,163
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real estate - residential
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	1,187	559
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Installment loans to individuals
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	50	34
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Lease financing receivable
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Other loans
Age Analysis of Past Due Loans by Class of Loans [Abstract]
Total Past Due	$ 0	$ 0