Allowance for loan losses and credit quality Allocation of Investment in Loans, by Impairment Methodology (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	$ 5,144	$ 5,241
Collectively evaluated for impairment	671,387	665,003
Total	676,531	670,244
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1,488	1,515
Collectively evaluated for impairment	188,932	190,610
Total	190,420	192,125
Construction Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	218	223
Collectively evaluated for impairment	53,989	69,394
Total	54,207	69,617
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	3,158	3,204
Collectively evaluated for impairment	301,046	286,679
Total	304,204	289,883
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	280	299
Collectively evaluated for impairment	47,353	47,400
Total	47,633	47,699
Consumer [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,460	3,562
Total	3,460	3,562
Municipal [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	76,607	67,358
Total	$ 76,607	$ 67,358

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No definition available.

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- Definition

The balance of financing receivables that were collectively evaluated for impairment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

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- Definition

The balance of financing receivables that were individually evaluated for impairment.

+ References

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118952595&loc=d3e4428-111522

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