Fair value estimates - Carrying and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Investment securities:
Available-for-sale	$ 418,125	$ 477,703
Common equity securities	81	110
Held-to-maturity	77,073	76,563
Mortgage servicing rights	906	914
Financial liabilities:
Subordinated debentures	33,000	33,000
Carrying Value
Financial assets:
Cash and due from banks	140,583	37,868
Investment securities:
Available-for-sale	418,125	477,703
Common equity securities	81	110
Held-to-maturity	89,705	91,179
Net loans	2,792,599	2,702,644
Accrued interest receivable	11,678	11,715
Mortgage servicing rights	906	914
Restricted equity securities (FHLB and other)	4,887	9,630
Interest rate floor	1	1
Interest rate swaps	18,485	21,794
Total assets	3,477,050	3,353,558
Financial liabilities:
Deposits	3,235,967	3,046,598
Short-term borrowings	17,280	114,930
Long-term debt	25,000	555
Subordinated debentures	33,000	33,000
Accrued interest payable	2,304	903
Interest rate floor	1,980
Interest rate swap	17,914	21,466
Total liabilities	3,333,445	3,217,452
Fair Value
Financial assets:
Cash and due from banks	140,583	37,868
Investment securities:
Available-for-sale	418,125	477,703
Common equity securities	81	110
Held-to-maturity	77,073	76,563
Net loans	2,629,921	2,562,780
Accrued interest receivable	11,678	11,715
Mortgage servicing rights	1,747	1,762
Restricted equity securities (FHLB and other)	4,887	9,630
Interest rate floor	1	1
Interest rate swaps	18,485	21,794
Total assets	3,302,580	3,199,926
Financial liabilities:
Deposits	3,229,495	3,035,615
Short-term borrowings	17,280	114,743
Long-term debt	24,982	555
Subordinated debentures	31,898	53,998
Accrued interest payable	2,304	903
Interest rate floor	1,980
Interest rate swap	17,914	21,466
Total liabilities	3,325,853	3,227,280
Level 1
Financial assets:
Cash and due from banks	140,583	37,868
Investment securities:
Available-for-sale	181,564	180,297
Common equity securities	81	110
Level 2
Investment securities:
Available-for-sale	236,561	294,706
Held-to-maturity	77,073	76,563
Accrued interest receivable	11,678	11,715
Mortgage servicing rights	1,747	1,762
Restricted equity securities (FHLB and other)	4,887	9,630
Interest rate floor	1	1
Interest rate swaps	18,485	21,794
Financial liabilities:
Deposits	3,229,495	3,035,615
Short-term borrowings	17,280	114,743
Long-term debt	24,982	555
Subordinated debentures	31,898	53,998
Accrued interest payable	2,304	903
Interest rate floor	1,980
Interest rate swap	17,914	21,466
Level 3
Investment securities:
Net loans	$ 2,629,921	$ 2,562,780