Loans, net and allowance for credit losses - Changes in Allowance for Loan Losses Account by Major Classification of Loans (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Allowance for loan losses:
Beginning Balance	$ 22,597	$ 25,444	$ 21,895	$ 27,472
Charge-offs	(135)	(77)	(243)	(152)
Recoveries	65	52	167	118
Provisions (credits)	596	(2,201)	1,304	(937)
Ending balance	23,123	23,218	23,123	23,218
Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				(3,283)
Adjusted Balance
Allowance for loan losses:
Beginning Balance				24,189
Commercial
Allowance for loan losses:
Beginning Balance	2,287	2,481	2,272	4,365
Charge-offs	(41)		(46)	(4)
Recoveries	25	5	80	5
Provisions (credits)	(100)	265	(135)	68
Ending balance	2,171	2,751	2,171	2,751
Commercial \| Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				(1,683)
Commercial \| Adjusted Balance
Allowance for loan losses:
Beginning Balance				2,682
Municipal
Allowance for loan losses:
Beginning Balance	698	2,318	788	1,247
Provisions (credits)	13	(1,491)	(77)	(1,167)
Ending balance	711	827	711	827
Municipal \| Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				747
Municipal \| Adjusted Balance
Allowance for loan losses:
Beginning Balance				1,994
Commercial real estate
Allowance for loan losses:
Beginning Balance	14,470	15,692	14,153	17,915
Recoveries				1
Provisions (credits)	686	(731)	1,003	389
Ending balance	15,156	14,961	15,156	14,961
Commercial real estate \| Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				(3,344)
Commercial real estate \| Adjusted Balance
Allowance for loan losses:
Beginning Balance				14,571
Residential real estate
Allowance for loan losses:
Beginning Balance	4,258	3,868	3,782	3,072
Recoveries	2	3	4	19
Provisions (credits)	(30)	(104)	444	(291)
Ending balance	4,230	3,767	4,230	3,767
Residential real estate \| Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				967
Residential real estate \| Adjusted Balance
Allowance for loan losses:
Beginning Balance				4,039
Consumer
Allowance for loan losses:
Beginning Balance	884	1,085	900	873
Charge-offs	(94)	(77)	(197)	(148)
Recoveries	38	44	83	93
Provisions (credits)	27	(140)	69	64
Ending balance	$ 855	$ 912	$ 855	912
Consumer \| Cumulative impact of adoption \| ASC 326
Allowance for loan losses:
Beginning Balance				30
Consumer \| Adjusted Balance
Allowance for loan losses:
Beginning Balance				$ 903

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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