Loans, net and allowance for loan 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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Allowance for loan losses:
Beginning Balance	$ 28,407	$ 26,783	$ 28,383	$ 27,344
Charge-offs	(98)	(190)	(453)	(385)
Recoveries	115	46	194	180
Provisions (credits)	950	100	1,250	(400)
Ending balance	29,374	26,739	29,374	26,739
Commercial
Allowance for loan losses:
Beginning Balance	7,593	8,215	8,453	8,734
Charge-offs			(161)	(15)
Recoveries	20	18	29	79
Provisions (credits)	153	287	(555)	(278)
Ending balance	7,766	8,520	7,766	8,520
Real estate Commercial
Allowance for loan losses:
Beginning Balance	16,789	14,703	15,928	14,559
Charge-offs		(144)	(132)	(240)
Recoveries	61	8	77	66
Provisions (credits)	719	(286)	1,696	(104)
Ending balance	17,569	14,281	17,569	14,281
Real estate Residential
Allowance for loan losses:
Beginning Balance	3,255	2,994	3,209	3,129
Charge-offs	(2)	(2)	(2)	(24)
Recoveries		1	3	2
Provisions (credits)	(33)	76	10	(38)
Ending balance	3,220	3,069	3,220	3,069
Consumer
Allowance for loan losses:
Beginning Balance	770	871	793	922
Charge-offs	(96)	(44)	(158)	(106)
Recoveries	34	19	85	33
Provisions (credits)	111	23	99	20
Ending balance	$ 819	$ 869	$ 819	$ 869