Allowance for loan losses and credit quality New Troubled Debt Restructured Loans (Details) - Residential Real Estate [Member] $ in Thousands	3 Months Ended
Mar. 31, 2020 USD ($) loans	Mar. 31, 2019 USD ($) loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
New TDRs, Number of Loans \| loans	0	1
New TDRs, Pre-Modification Outstanding Recorded Investment	$ 0	$ 77
New TDRs, Post-Modification Outstanding Recorded Investment	$ 0	$ 79

Number of financing receivables that have been modified by troubled debt restructurings during the reporting period.

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

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=118936363&loc=SL6953676-111524

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, before troubled debt restructuring, of financing receivable to be modified.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- Details

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