Loans - Modification Statuses by Portfolio Segment (Details) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($) loan	Sep. 30, 2020 USD ($) loan	Dec. 31, 2020 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	64	78	74
Percentage of loans receivable, by type	100.00%	100.00%	100.00%
Balance \| $	$ 1,617,212	$ 1,436,646	$ 1,476,761
Commercial/Municipal Loan Modifications \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	605
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 234,334
Percentage of balance	100.00%
Commercial/Municipal Loan Modifications \| Paid Off \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	156
Percentage of loans receivable, by type	26.00%
Balance \| $	$ 35,130
Percentage of balance	15.00%
Commercial/Municipal Loan Modifications \| Charged Off \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1
Percentage of loans receivable, by type	0.00%
Balance \| $	$ 66
Percentage of balance	0.00%
Commercial/Municipal Loan Modifications \| Subsequent Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	2
Percentage of loans receivable, by type	0.00%
Balance \| $	$ 1,014
Percentage of balance	0.00%
Commercial/Municipal Loan Modifications \| Still in Original Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1
Percentage of loans receivable, by type	0.00%
Balance \| $	$ 125
Percentage of balance	0.00%
Commercial/Municipal Loan Modifications \| Out of Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	445
Percentage of loans receivable, by type	74.00%
Balance \| $	$ 197,999
Percentage of balance	85.00%
Residential Real Estate Modifications \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	377
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 52,578
Percentage of balance	100.00%
Residential Real Estate Modifications \| Paid Off \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	73
Percentage of loans receivable, by type	20.00%
Balance \| $	$ 12,694
Percentage of balance	24.00%
Residential Real Estate Modifications \| Subsequent Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	53
Percentage of loans receivable, by type	14.00%
Balance \| $	$ 5,405
Percentage of balance	10.00%
Residential Real Estate Modifications \| Still in Original Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1
Percentage of loans receivable, by type	0.00%
Balance \| $	$ 22
Percentage of balance	0.00%
Residential Real Estate Modifications \| Out of Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	250
Percentage of loans receivable, by type	66.00%
Balance \| $	$ 34,457
Percentage of balance	66.00%
Consumer Loan Modifications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1	1	1
Percentage of loans receivable, by type	1.40%	1.90%	1.80%
Balance \| $	$ 23,333	$ 27,323	$ 25,857
Consumer Loan Modifications \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	69
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 1,010
Percentage of balance	100.00%
Consumer Loan Modifications \| Paid Off \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	23
Percentage of loans receivable, by type	34.00%
Balance \| $	$ 209
Percentage of balance	21.00%
Consumer Loan Modifications \| Charged Off \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1
Percentage of loans receivable, by type	1.00%
Balance \| $	$ 10
Percentage of balance	1.00%
Consumer Loan Modifications \| Subsequent Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	2
Percentage of loans receivable, by type	3.00%
Balance \| $	$ 43
Percentage of balance	4.00%
Consumer Loan Modifications \| Out of Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	43
Percentage of loans receivable, by type	62.00%
Balance \| $	$ 748
Percentage of balance	74.00%