Loans, Allowance for Credit Losses and Credit Quality Schedule of Debtor Troubled Debt Restructurings, Subsequent Period (Details)	3 Months Ended	9 Months Ended
Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract	Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 0	$ 0	$ 0	$ 0
Financing Receivable, Modifications, Number of Contracts \| contract	5	5	17	9
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 827,000	$ 448,000	$ 3,580,000	$ 784,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 827,000	$ 453,000	$ 3,639,000	$ 789,000
Commercial And Industrial [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract	2	1	5	2
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 83,000	$ 87,000	$ 391,000	$ 184,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 83,000	$ 87,000	$ 391,000	$ 184,000
Commercial Real Estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract	3	1	8	2
Financing Receivable, Troubled Debt Restructuring, Premodification	$ 744,000	$ 133,000	$ 2,518,000	$ 283,000
Financing Receivable, Troubled Debt Restructuring, Postmodification	$ 744,000	$ 133,000	$ 2,518,000	$ 283,000
Small Business [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract	0	1	2	2
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 19,000	$ 112,000	$ 33,000
Financing Receivable, Troubled Debt Restructuring, Postmodification		19,000	$ 88,000	$ 33,000
Residential Real Estate [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract	0		2	1
Financing Receivable, Troubled Debt Restructuring, Premodification		163,000	$ 559,000	$ 163,000
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 168,000	$ 642,000	$ 168,000
Home Equity Line of Credit [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract		1		2
Financing Receivable, Troubled Debt Restructuring, Premodification		$ 46,000		$ 121,000
Financing Receivable, Troubled Debt Restructuring, Postmodification		$ 46,000		$ 121,000
Residential Mortgage [Member]
Troubled Debt Restructuring, Debtor, Subsequent Periods [Line Items]
Financing Receivable, Modifications, Number of Contracts \| contract		1

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

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=121611835&loc=SL6953676-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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