Allowance for loan losses and credit quality Troubled Debt Restured Loans (Details) $ in Thousands	Sep. 30, 2015 USD ($) loans	Dec. 31, 2014 USD ($) loans
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans, Number of Loans	16	11
Troubled Debt Restructured Loans, Principal Balance \| $	$ 2,240	$ 1,691
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans, Number of Loans	10	5
Troubled Debt Restructured Loans, Principal Balance \| $	$ 1,185	$ 704
Construction Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans, Number of Loans	1	3
Troubled Debt Restructured Loans, Principal Balance \| $	$ 93	$ 276
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructured Loans, Number of Loans	5	3
Troubled Debt Restructured Loans, Principal Balance \| $	$ 962	$ 711

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- 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=49124121&loc=SL6953676-111524

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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

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