Allowance for loan losses and credit quality Troubled Debt Restured Loans (Details) $ in Thousands	Mar. 31, 2020 USD ($) loans	Dec. 31, 2019 USD ($) loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructured Loans, Number of Loans \| loans	40	40
Troubled Debt Restructured Loans, Principal Balance \| $	$ 2,805	$ 2,871
Residential Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructured Loans, Number of Loans \| loans	25	25
Troubled Debt Restructured Loans, Principal Balance \| $	$ 1,488	$ 1,515
Construction Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructured Loans, Number of Loans \| loans	2	2
Troubled Debt Restructured Loans, Principal Balance \| $	$ 96	$ 100
Commercial Real Estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructured Loans, Number of Loans \| loans	8	8
Troubled Debt Restructured Loans, Principal Balance \| $	$ 950	$ 966
Commercial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Troubled Debt Restructured Loans, Number of Loans \| loans	5	5
Troubled Debt Restructured Loans, Principal Balance \| $	$ 271	$ 290

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

+ References

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Amount of financing receivable modified as troubled debt restructuring.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=118939409&loc=d3e18845-111554

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