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, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Allowance for loan losses:
Beginning Balance	$ 25,444	$ 28,407	$ 27,472	$ 28,383
Charge-offs	(77)	(98)	(152)	(453)
Recoveries	52	115	118	194
Provisions (credits)	(2,201)	950	(937)	1,250
Ending balance	23,218	29,374	23,218	29,374
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	2,481	6,427	4,365	7,466
Charge-offs			(4)	(161)
Recoveries	5	20	5	29
Provisions (credits)	265	75	68	(812)
Ending balance	2,751	6,522	2,751	6,522
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	2,318	1,166	1,247	987
Provisions (credits)	(1,491)	78	(1,167)	257
Ending balance	827	1,244	827	1,244
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	15,692	16,789	17,915	15,928
Charge-offs				(132)
Recoveries		61	1	77
Provisions (credits)	(731)	719	389	1,696
Ending balance	14,961	17,569	14,961	17,569
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	3,868	3,255	3,072	3,209
Charge-offs		(2)		(2)
Recoveries	3		19	3
Provisions (credits)	104	(33)	(291)	10
Ending balance	3,767	3,220	3,767	3,220
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	1,085	770	873	793
Charge-offs	(77)	(96)	(148)	(158)
Recoveries	44	34	93	85
Provisions (credits)	(140)	111	64	99
Ending balance	$ 912	$ 819	912	$ 819
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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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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+ 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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