Loans - Summary of interest income on impaired loans (Details 4) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	$ 49	$ 93	$ 99	$ 230
Cash Basis Interest Income Recognized	49	93	99	230
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	2	3	7	6
Cash Basis Interest Income Recognized	2	3	7	6
Commercial real estate | Non Owner occupied
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	24	73	45	178
Cash Basis Interest Income Recognized	24	73	45	178
Residential real estate | Secured by first liens
Financing Receivable, Impaired [Line Items]
Interest Income Recognized	16	9	31	30
Cash Basis Interest Income Recognized	16	9	31	30
Residential real estate | Secured by junior liens
Financing Receivable, Impaired [Line Items]
Interest Income Recognized		1		3
Cash Basis Interest Income Recognized		1		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	7	7	16	13
Cash Basis Interest Income Recognized	7	7	16	13
Consumer installment
Financing Receivable, Impaired [Line Items]
Interest Income Recognized
Cash Basis Interest Income Recognized