Allowance for loan losses and credit quality Allocation of the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	$ 196	$ 66
Collectively evaluated for impairment	5,926	5,673
Total allocated	6,122	5,739	$ 5,408
Residential Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	39	47
Collectively evaluated for impairment	1,353	1,321
Total allocated	1,392	1,368	1,361
Construction Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	774	617
Total allocated	774	617	488
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	149	9
Collectively evaluated for impairment	3,029	2,924
Total allocated	3,178	2,933	2,707
Commercial [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	8	10
Collectively evaluated for impairment	386	344
Total allocated	394	354	395
Consumer [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	23	23
Total allocated	23	23	30
Municipal [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	76	82
Total allocated	76	82	64
Unallocated [Member]
Financing Receivable, Allowance for Credit Loss [Line Items]
Individually evaluated for impairment	0	0
Collectively evaluated for impairment	285	362
Total allocated	$ 285	$ 362	$ 363

The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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 (g)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for 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 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 30
-Section 50
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-URI http://asc.fasb.org/extlink&oid=118939070&loc=d3e15032-111544

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
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-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953423-111524

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-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
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