Loans - Summary of interest income on impaired loans (Details 4) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	$ 35	$ 108	$ 134	$ 338
Cash Basis Interest Income Recognized	35	108	134	338
Commercial, financial, and agricultural | Commercial
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Commercial, financial, and agricultural | Financial
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Commercial, financial, and agricultural | Agricultural
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Commercial, financial, and agricultural | Equity lines
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Commercial, financial, and agricultural | Other
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Commercial real estate | Owner occupied
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	4	43	11	118
Cash Basis Interest Income Recognized	4	43	11	118
Commercial real estate | Non Owner occupied
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	13	52	58	161
Cash Basis Interest Income Recognized	13	52	58	161
Residential real estate | Secured by first liens
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	8	7	39	37
Cash Basis Interest Income Recognized	8	7	39	37
Residential real estate | Secured by junior liens
Financing Receivable, Impaired [Line Items]
Interest Income Recognized				3
Cash Basis Interest Income Recognized				3
Acquisition, development and construction | Residential
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized
Acquisition, development and construction | Other
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	10	6	26	19
Cash Basis Interest Income Recognized	10	6	26	19
Consumer
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized