Allowance for loan losses and credit quality Allocation of Investment in Loans, by Impairment Methodology (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	$ 5,241	$ 4,425
Collectively evaluated for impairment	665,003	638,036
Total	670,244	642,461
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	1,515	1,678
Collectively evaluated for impairment	190,610	185,642
Total	192,125	187,320
Construction Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	223	119
Collectively evaluated for impairment	69,394	55,203
Total	69,617	55,322
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	3,204	2,276
Collectively evaluated for impairment	286,679	274,224
Total	289,883	276,500
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	299	352
Collectively evaluated for impairment	47,400	46,876
Total	47,699	47,228
Consumer [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	3,562	3,241
Total	3,562	3,241
Municipal [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	67,358	72,850
Total	$ 67,358	$ 72,850

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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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