Loans - Modification Statuses by Portfolio Segment (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) loan	Mar. 31, 2020 USD ($) loan	Dec. 31, 2020 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	73	81	74
Percentage of loans receivable, by type	100.00%	100.00%	100.00%
Balance \| $	$ 1,516,772	$ 1,344,208	$ 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	606
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 239,244
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	90
Percentage of loans receivable, by type	15.00%
Balance \| $	$ 14,002
Percentage of balance	6.00%
Commercial/Municipal Loan Modifications \| Subsequent Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	30
Percentage of loans receivable, by type	5.00%
Balance \| $	$ 30,435
Percentage of balance	13.00%
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	11
Percentage of loans receivable, by type	2.00%
Balance \| $	$ 1,595
Percentage of balance	1.00%
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	475
Percentage of loans receivable, by type	78.00%
Balance \| $	$ 193,212
Percentage of balance	80.00%
Residential Real Estate Modifications \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	363
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 51,677
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	41
Percentage of loans receivable, by type	11.00%
Balance \| $	$ 8,269
Percentage of balance	16.00%
Residential Real Estate Modifications \| Subsequent Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	136
Percentage of loans receivable, by type	38.00%
Balance \| $	$ 16,595
Percentage of balance	32.00%
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	16
Percentage of loans receivable, by type	4.00%
Balance \| $	$ 1,853
Percentage of balance	4.00%
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	170
Percentage of loans receivable, by type	47.00%
Balance \| $	$ 24,960
Percentage of balance	48.00%
Consumer Loan Modifications
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	1	0	1
Percentage of loans receivable, by type	1.60%	2.20%	1.80%
Balance \| $	$ 24,117	$ 29,262	$ 25,857
Consumer Loan Modifications \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	68
Percentage of loans receivable, by type	100.00%
Balance \| $	$ 1,082
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	17
Percentage of loans receivable, by type	25.00%
Balance \| $	$ 129
Percentage of balance	12.00%
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 \| $	$ 62
Percentage of balance	6.00%
Consumer Loan Modifications \| Still in Original 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 \| $	$ 27
Percentage of balance	2.00%
Consumer Loan Modifications \| Out of Modification \| Exemption from Troubled Debt Restructure Designation, CARES Act
Accounts, Notes, Loans and Financing Receivable [Line Items]
Units \| loan	47
Percentage of loans receivable, by type	69.00%
Balance \| $	$ 864
Percentage of balance	80.00%