Loans - Troubled debt restructurings (Details 6) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2016 USD ($) Loan	Dec. 31, 2015 USD ($) Loan
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	17	19
Recorded Investment \| $	$ 7,583	$ 8,636
Commercial, financial, and agricultural \| Commercial
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	1	1
Recorded Investment \| $	$ 751	$ 810
Commercial, financial, and agricultural \| Financial
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $
Commercial, financial, and agricultural \| Agricultural
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $
Commercial, financial, and agricultural \| Equity lines
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $
Commercial, financial, and agricultural \| Other
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $
Commercial real estate \| Owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	2	1
Recorded Investment \| $	$ 3,681	$ 273
Commercial real estate \| Non Owner occupied
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	3	4
Recorded Investment \| $	$ 1,735	$ 4,499
Residential real estate \| Secured by first liens
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	9	10
Recorded Investment \| $	$ 1,026	$ 1,140
Residential real estate \| Secured by junior liens
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	1	1
Recorded Investment \| $	$ 88	$ 94
Acquisition, development and construction real estate \| Residential
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $
Acquisition, development and construction real estate \| Other
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan	1	2
Recorded Investment \| $	$ 302	$ 1,820
Consumer
Financing Receivable, Modifications [Line Items]
Number of Loans \| Loan
Recorded Investment \| $

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

Name:	us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

+ Details

Name:	us-gaap_FinancingReceivableModificationsRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant