Fair value of financial instruments - Carrying and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Investment securities:
Available-for-sale	$ 398,927	$ 477,703
Common equity securities	98	110
Held-to-maturity	71,698	76,563
Mortgage servicing rights	870	914
Financial liabilities:
Subordinated debentures	33,000	33,000
Carrying Value
Financial assets:
Cash and due from banks	187,365	37,868
Investment securities:
Available-for-sale	398,927	477,703
Common equity securities	98	110
Held-to-maturity	84,851	91,179
Net loans	2,828,002	2,702,644
Accrued interest receivable	12,734	11,715
Mortgage servicing rights	870	914
Restricted equity securities (FHLB and other)	5,180	9,630
Interest rate floor		1
Interest rate swaps	19,278	21,794
Total assets	3,537,555	3,353,558
Financial liabilities:
Deposits	3,279,037	3,046,598
Short-term borrowings	17,590	114,930
Long-term debt	25,000	555
Subordinated debentures	33,000	33,000
Accrued interest payable	5,765	903
Interest rate swap	18,808	21,466
Total liabilities	3,379,200	3,217,452
Fair Value
Financial assets:
Cash and due from banks	187,365	37,868
Investment securities:
Available-for-sale	398,927	477,703
Common equity securities	98	110
Held-to-maturity	71,698	76,563
Net loans	2,593,151	2,562,780
Accrued interest receivable	12,734	11,715
Mortgage servicing rights	1,745	1,762
Restricted equity securities (FHLB and other)	5,180	9,630
Interest rate floor		1
Interest rate swaps	19,278	21,794
Total assets	3,290,426	3,199,926
Financial liabilities:
Deposits	3,274,774	3,035,615
Short-term borrowings	17,590	114,743
Long-term debt	24,924	555
Subordinated debentures	45,504	53,998
Accrued interest payable	5,765	903
Interest rate swap	18,808	21,466
Total liabilities	3,387,365	3,227,280
Level 1
Financial assets:
Cash and due from banks	187,365	37,868
Investment securities:
Available-for-sale	184,057	180,297
Common equity securities	98	110
Level 2
Investment securities:
Available-for-sale	214,870	294,706
Held-to-maturity	71,698	76,563
Accrued interest receivable	12,734	11,715
Mortgage servicing rights	1,745	1,762
Restricted equity securities (FHLB and other)	5,180	9,630
Interest rate floor		1
Interest rate swaps	19,278	21,794
Financial liabilities:
Deposits	3,274,774	3,035,615
Short-term borrowings	17,590	114,743
Long-term debt	24,924	555
Subordinated debentures	45,504	53,998
Accrued interest payable	5,765	903
Interest rate swap	18,808	21,466
Level 3
Investment securities:
Net loans	$ 2,593,151	$ 2,562,780