Allowance for Loan Losses Financing Receivable and Allowance Element by Class (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 11,639	$ 11,232	$ 10,729	$ 10,138
Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	3,742	3,567	3,872	3,988
Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	365	255	434	396
Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	3,329	3,541	3,358	1,780
Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	27	24	20	18
Residential | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	25	34	36	44
Residential | Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,024	1,235	1,130	1,288
Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,078	730	692	807
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	867	630	545	559
Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,182	1,216	$ 642	$ 1,258
Specific Reserves on Loans Evaluated Individually for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,213	2,308
Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	251	260
Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Specific Reserves on Loans Evaluated Individually for Impairment | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,273	1,696
Specific Reserves on Loans Evaluated Individually for Impairment | Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Specific Reserves on Loans Evaluated Individually for Impairment | Residential | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Specific Reserves on Loans Evaluated Individually for Impairment | Residential | Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	237	335
Specific Reserves on Loans Evaluated Individually for Impairment | Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	447	17
Specific Reserves on Loans Evaluated Individually for Impairment | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	5	0
Specific Reserves on Loans Evaluated Individually for Impairment | Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
General Reserves on Loans Based on Historical Loss Experience
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,983	2,085
General Reserves on Loans Based on Historical Loss Experience | Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	729	742
General Reserves on Loans Based on Historical Loss Experience | Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	76	57
General Reserves on Loans Based on Historical Loss Experience | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	430	414
General Reserves on Loans Based on Historical Loss Experience | Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
General Reserves on Loans Based on Historical Loss Experience | Residential | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	5	12
General Reserves on Loans Based on Historical Loss Experience | Residential | Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	153	326
General Reserves on Loans Based on Historical Loss Experience | Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	130	263
General Reserves on Loans Based on Historical Loss Experience | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	460	271
General Reserves on Loans Based on Historical Loss Experience | Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Reserves for Qualitative Factors
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	6,261	5,623
Reserves for Qualitative Factors | Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	2,762	2,565
Reserves for Qualitative Factors | Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	289	198
Reserves for Qualitative Factors | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,626	1,431
Reserves for Qualitative Factors | Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	27	24
Reserves for Qualitative Factors | Residential | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	20	22
Reserves for Qualitative Factors | Residential | Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	634	574
Reserves for Qualitative Factors | Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	501	450
Reserves for Qualitative Factors | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	402	359
Reserves for Qualitative Factors | Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	1,182	1,216
Unallocated Reserves | Commercial | Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Commercial | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Commercial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Municipal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Residential | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Residential | Term
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves | Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 1,182	$ 1,216