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	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Allowance for loan losses:
Beginning Balance	$ 23,218	$ 29,374	$ 27,472	$ 28,383
Charge-offs	(65)	(101)	(217)	(554)
Recoveries	23	99	141	293
Provisions (credits)	(166)	450	(1,103)	1,700
Ending balance	23,010	29,822	23,010	29,822
Cumulative impact of adoption \| ASU 2016-13
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	2,751	6,522	4,365	7,466
Charge-offs			(4)	(161)
Recoveries	4	10	9	39
Provisions (credits)	(504)	(12)	(436)	(824)
Ending balance	2,251	6,520	2,251	6,520
Commercial \| Cumulative impact of adoption \| ASU 2016-13
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	827	1,244	1,247	987
Provisions (credits)	40	7	(1,127)	264
Ending balance	867	1,251	867	1,251
Municipal \| Cumulative impact of adoption \| ASU 2016-13
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	14,961	17,569	17,915	15,928
Charge-offs		(15)		(147)
Recoveries		32	1	109
Provisions (credits)	134	437	523	2,133
Ending balance	15,095	18,023	15,095	18,023
Commercial real estate \| Cumulative impact of adoption \| ASU 2016-13
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	3,767	3,220	3,072	3,209
Charge-offs				(2)
Recoveries	3	1	22	4
Provisions (credits)	(128)	9	(163)	19
Ending balance	3,898	3,230	3,898	3,230
Residential real estate \| Cumulative impact of adoption \| ASU 2016-13
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	912	819	873	793
Charge-offs	(65)	(86)	(213)	(244)
Recoveries	16	56	109	141
Provisions (credits)	36	9	100	108
Ending balance	$ 899	$ 798	899	$ 798
Consumer \| Cumulative impact of adoption \| ASU 2016-13
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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No definition available.

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+ 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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+ 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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